LSA Electronics Warp 1 Stereo Power Amplifier Review

The LSA Warp1 amplifier impressed with a natural ease and above-average clarity. The sound staging and imaging were first-rate while the bass response bested my reference Class D stereo amp by light years. It’s an impressive amp in a lightweight package and ridiculously low in price.

LSA currently offers two solid state power amps and two tube integrated amps through their retail outlet, Underwood HiFi. All their amplifiers are thoughtfully designed, well assembled, and of high quality. Surprisingly, they are all quite affordable and provide excellent performance-to-price ratios.

The Warp 1 amp under review here is the smaller of the two solid-state amps. It is a Class D topology, and the manufacturer claims it is a “150 WPC” stereo amp. Being Class D, the amp chassis is small and light. It also exhibits high electrical efficiency. Please read below to learn more about this neat little amp and how it performs.

The LSA Warp-1 Power Amplifier is predicated on the Texas Instruments TPA3255 PurePath™ Ultra-HD Class D amplifier module. The TI chip can be configured in several ways, and it is implemented in stereo configuration for this amplifier. The Warp-1 was designed by Viet Nguyen who has some unique implementation concepts that I will describe below.

First things first, LSA claims the TI chip enjoys a “State of the Art Layout”. They describe this layout by explaining the TI chip is mounted on a dual-layer PCB board. The PCB is an extra thick 2mm FR4 with 2oz (70um thick) copper traces and electroless nickel immersion gold (ENIG) finish. The two layers of the circuit board are “stitched together with thousands of vias wherever an ultra-low impedance path was needed.” The vias are drilled holes between the boards with metal-plated walls that interconnect the two layers of the PCB. LSA claims this setup provides improved signal transfer.

Mr. Nguyen states that he kept the signal paths short. Additionally, the grounding scheme is a star hub scheme with the power to the board entering near the physical center of the circuit board. This ensures all critical components share the same ground plane reference.

I don’t have the most extensive experience with Class D amplifiers, but I can state unequivocally that early examples suffered because of poorly designed output filters. I honestly couldn’t even listen to early Class D amplifiers for more than a few minutes. That all changed when I reviewed Phase Technology’s dARTs system. The Phase Tech crew explained the reason their amplifiers were so good is because of the attention to detail with regard to the filter section. Mr. Nguyen importantly highlights that LSA employed CoilCraft flat copper wire SER shielded inductors in the output filters. These inductors provide high-current and low-distortion playback.

LSA provides few details regarding the power supply. They state that the power supply is a 600W switch-mode operation power supply. It is claimed to be custom-made for the amplifier. Quoting from their promotional materials, “unlike most SMPS, the power supply in the Warp-1 can be connected to large smoothing capacitors without going into hiccup mode.” Nice.

Another design highlight centers around the input buffer. It is located at the input jacks at the rear of the case. This buffer is based on TI OAP1656 opamps for signal conversion and amplification. The Warp-1 will accept balanced XLR/TRS inputs by way of combo Neutrik Connectors. You can also run this amp off unbalanced RCAs. The buffer circuit gives priority to the balanced inputs but will automatically switch to whatever input is active and disconnects (via a relay) the SE RCA input to prevent signal overload.

The TI amplifier module features differential analog inputs, and the input buffer uses a Texas Instruments OPA1637 balanced line driver to power the balanced inputs of the TPA3255 amplifier chip.

Interestingly, the input buffer has adjustable amplifier gain settings by way of DIP switches. The gain on the input buffer can be selected from 0dB, 6dB, 14dB, and 20dB. The TPA3255 amp has an intrinsic 22dB of gain so the setting from the factory is 6dB for an overall 28dB gain. Some applications may require lower gain so 0dB can be selected for an overall 22dB of gain. 14dB will give an overall 36dB of gain which might be useful when playing from a less powerful source like a smartphone. Although a 20dB setting is provided, it should not be used as it will likely overload the input signal and seriously degrade the sound.

This is all presented in a lightweight, aluminum case that has a fresh look with a black faceplate and cast aluminum elsewhere. The feet are the substantial, dampening kind. In the back, you have the two sets of inputs, a pair of five-way binding posts, the three-prong IEC input cup, a mains power switch, and a reset button! The front panel has a light-up power toggle, a power status LED, and three additional LEDs that indicate three possible fault states. I did not like the very bright LEDs when the amp was on and wished for a panel defeat switch. I, like many audiophiles, enjoy listening at night and in the dark. These front panel LEDs were way too bright.

I normally bench test amplifiers when I get them in for review. With my testing system, I have the capability to test amplifiers’ maximum power output along with basic frequency response, THD+N, and IMD tests. Unfortunately, my testing rig was down for the count when I had the Warp-1 amplifier in review. I am getting upgraded testing components at this time, but this downtime meant that I was not able to run my own independent tests of the LSA Warp 1 amp.

I do not claim to be an objectivist and I have had my mind blown in audio so many times, that I don’t even know for sure what tests really mean on most days. As I started this review, I was quoted a lot of varying specifications for the amp, whether via email from the principals or on their website. Furthermore, LSA does not provide any FTC specs for the Warp 1 amp.

The basic power rating from LSA states 150 WPC into 8 Ohms or 250 WPC into 4 Ohms. I think this power specification comes from TI. It is the maximum rated power found in the TI TPA3255 spec sheet. The actual power could not be more than this and the actual number would hinge on the power supply and other design/environmental factors.

Mr. Nguyen did provide several detailed distortion plots from his personal testing rig. This testing rig is posted below, and the various components/boards are labeled for your convenience.

The results shown in the below plots are 108 W into 10 Ohms 0.27% THD and 12 W 10 Ohm 0.0033%. These are good results but do not directly correspond with the claims on the LSA website. For their part, LSA has committed to updating the website to eliminate the confusion on this matter.

I am going with the plots provided by LSA versus the website. The tests below show a variance in the distortion profile between the two plots. The 12-Watt test indicates that the distortion profile comprises odd and even harmonics in what would be a pleasing-sounding mix and probably has some bearing on the sweet sound of the amplifier. The 108-Watt test is dominated by odd-order harmonics that do recede in a similarly mellifluous manner.

This appears to be a somewhat odd result and I went back just now to review tests I got when testing other Class D amplifiers such as the NAD M 22. That amp had more of all harmonics during the higher power output tests. So, the Warp 1 amplifier has somewhat perplexing test results.

With regards to the S/N ratio, LSA states, “These components and techniques combine together to yield an amplifier that has a performance in the rarefied air of 130dB signal to noise ratio. Even without a source playing, the Warp-1 will be absolutely silent with the ear pressed to the speaker cone – you cannot tell the amp is turned on unless the LEDs were glowing. This amp can be used in every type and sort of High-Performance Audio System with spectacular results.” As of this writing, the website states a S/N ratio of 115 dB.

All that said, the amplifier had plenty of power to drive my VIVID Kaya 90 speakers to satisfying levels on all program material. We may not be able to compare LSA’s specification claims to claims of other manufacturers, but the amplifier performed well in actual use. My experience with the LSA Warp 1 amp was that more powerful amplifiers tended to convey greater inner detail than the Warp 1 and I will discuss this in my listening impressions below.

I placed the amplifier on the front shelf of my listening room where visiting amplifiers get the royal treatment! It was simple enough to set up. I ran the unit both balanced and unbalanced during my evaluation. Interconnects and speaker wires were Clarus Crimson. I also employed a Clarus Crimson power cable but no power conditioning – the unit was plugged straight into the wall.

The primary speakers used during the evaluation were my beloved VIVID Kaya 90s. I used both a passive preamp and alternately I used a tube preamp based on 12AX7 and 12AU7 tubes. Sources were an Oppo BDP 105D player and a Raspberry Pi running through a Topping D90 DAC as well as a Pass XP17 phono pre being fed by a VPI Prime with a Sumiko Blackbird cartridge.

OK, so despite my protestations regarding the manufacturer’s specification claims, this little amp rocked with a sweet sound and excellent bass response. The staging was also particularly satisfying.

Through the LSA Warp 1 amplifier, this album sounded as good as I ever remember hearing it. I’m sure a lot of you are like me when we go back to old music with new equipment – the songs don’t always click or even sound like they did back in the day. But with this system, I felt like the 15-year-old that was hearing this record for the first time. The thing that caught my ear first was the balanced sound throughout the frequency spectrum. Balanced, yes, but with subjectively more and deeper bass than I get with competing amplifiers.

The amplifier also passed along all the guitar distortion that I find so pleasing with the guitar playing on this lovely live album. The only critique I have of the LSA Warp 1 is that it didn’t convey all the inner detail that’s available in the extended “Dixie Chicken/Tripe Face Boogie” track. By comparison, the much more powerful D-Sonic amp I have on hand shone more light on the inner workings of this complex mix. But the LSA Warp 1 had far superior bass response.

Also on the Folk Singer album, the LSA did an excellent job of passing a tight, consistent sound stage. This character also played out on several albums throughout the review period.

THE LIVING SOUNDS AUDIO (LSA) WARP 1 STEREO POWER AMPLIFIER is an affordable, lightweight power amp that impresses with a transparent presentation predicated on a sweet sound with excellent bass and imaging.

The LSA Warp 1 amplifier impressed me with an easy musicality and excellent bass response. It had a natural ability to render a precise and engaging soundscape. The word that most often came to mind during my evaluation was “sweet”.

While this amp is not the last word in transparency, it was always fun and musical when listening. I am not sure what the amp’s real power output is, but it had no issues driving my VIVID Kaya 90’s in a rather large room: a nice match to be sure.

The LSA Warp 1 is also a lightweight, cool-running amp that is perhaps the best value in stereo amps at this time. You can’t go wrong, especially at the current sales price of $1,199 delivered! Recommended.