Product Review

InnerSound Solid State Stereo Preamplifier
September, 2002

Brett Johnson



Inputs: Six Line Level (One XLR - Five RCA)
Outputs: Five Line Level (One XLR - Four RCA)
MFR:  5 Hz - 200 kHz Minus 3 dB
Noise: - 100 dB
THD: 0.01%
Gain: 10 Volts Peak
Input Impedance: 47 kOhms
Output Impedance: 50 Ohms
Size: 1 3/4" H x 17" W x 8 1/2" D
Weight: 10 Pounds
MSRP: $2,995


The InnerSound preamp has been in my system for two months, and I have been reminded of why I got into this hobby in the first place. This simple preamp eliminated the focus on gadgetry that has dominated my life for the last ten or so years. I downloaded the user manual (White Paper) before I actually received the piece. It was shorter than the warnings about electrical hazards, and disclaimers, for many of the devices currently in my system. I was able to make it function without actually having the booklet close by to refer to. It did its job right out of the box, allowing me to focus simply on the source material and the pleasant experience of “Listening”.

I did not have to run around my room with a sound meter to determine if I was getting the “Set Up” right. There were no levels or crossovers to adjust, and there weren't any modes to configure. The preamp allows me to adjust the output level and the individual input gain. (I used the sound level meter to determine if my listening levels were similar for comparison with my other equipment.) I connected four cables to the inputs and two cables to the outputs, and once power was applied I was done. It was less than three minutes. It took me nearly three hours to get all of the interconnects properly configured for the last piece of equipment I moved into my system.

The Design

InnerSound chose to bundle the Home Theater Master remote control as the remote for their new preamp. I think that this was an excellent choice. I use the same remote in my current system. It is functional and reasonably intuitive; my whole family can operate it. The remote is well laid out, and is preprogrammed with a lot of device codes. I was able to program it to run both my Marantz CD/LD player and my Toshiba DVD player in minutes.

This is a very powerful remote that will operate up to eight components and includes the ability to have four Macros for sequential operations. Be aware that it can be reformatted or reset to default by the proper combination of button pushes. I discovered this one day as my two year old actually did it right before my eyes. (I thought that he was simply carrying it across the room to me, but he was randomly pushing buttons the whole time and “BINGO”.) InnerSound has also included some specific decals for labeling the remote once you have put it into service so the buttons are more easily identified. This is a nice touch, and I feel that it indicates the importance that this company places on the relationship they have with their customers.

The appearance of the InnerSound preamp is very clean. The lines are simple, and the switching is accessible without protruding from the faceplate. It is an elegant piece of equipment without being flashy. The display uses blue LEDs, which seem to be the color of choice for many of the latest components. The preamp is not very heavy, but it feels sturdy, while fit and finish are excellent. The preamp is available in both silver and black which will allow you to blend it with most other component lines.

The piece is very thin, and while space is usually at a premium in most systems, I would have liked a bit more room to make connections on the rear panel. I have big fingers, and some of my interconnects have large diameter ends. (Bad combination for small spaces, but it was no more crowded than most high density processors or home theater receivers.) The RCAs were very tight, and it was apparent that raw component tolerance (fit) was important to the manufacturer.

My listening room is 12'6” wide and 23' long with a ceiling height of 10' for the first 12 feet and 9'5” for the remaining 11 feet. My front speakers are 7' 10” apart and 24” from the front wall, and they are 34” off the floor. I was not using a subwoofer with any of the selections. I used the RCA unbalanced connections for all listening.

I started off listening to the stereo tracks of some very familiar concert DVDs, including the "Music for Montserrat" benefit concert and "Stop Making Sense", by The Talking Heads. These are pieces that I am really familiar with in both stereo and multi-channel. I was listening with the output set in a range of 50 to 75 dB, C weighted. I was listening to the audio portion of the DVD with the video section of my system shut down to eliminate visual cues from affecting the development of the audio image.

The sound stage was very involving, and the lack of a center channel was not apparent. Without the visual cues of the video, the center soundstage was full and articulate. Stereo imaging was excellent and the sound was clear. I usually judge impact based on the ability of even familiar passages to raise goose bumps. The InnerSound preamp did that without missing a beat. Tone and timbre were precise and rich, as they were intended to be when recorded. The InnerSound preamp added to my system by adding nothing at all, except gain.

I moved on to some favorite female voice with Carol Sloan ("The Real Thing") and Diana Krall ("Love Scenes"). Both women have very dynamic voices with very good lower tones. It was almost luxurious to feel in attendance as Diana ordered us to “Peel Me a Grape”! Carol Sloan's tracks were also a pleasure with her version of “Makin' Whoopee”, one of my favorite renditions of this song.

For me, female voice with lower range is one of the tougher things to reproduce well. While I understand that it is not the job of the preamp to do this in a system, my system sounded very good with the InnerSound Preamp in it.

I moved on to some southern fried blues and guitar with R.L. Burnside's "C'mon In". All of the fun and flaws of this recording were right in my face as the nearly out of tune guitar of the senior, and the very good drumming of his grandson, poured out of the front of the room as if I had rolled up their garage door in Mississippi.

The subtle beginnings of Revel's "Bolero" were easy to hear, even at very low volume levels (50 dB -55 dB), and the movement of Clapton's fingers was audible to the point of distraction throughout the unplugged version of "Tears in Heaven".

The InnerSound preamp uses a volume control knob that drives an optical-comparator circuit. I will not try to explain this in any way shape or form other than to say it is smooth and very precise. The details are in the white paper, and technically they make sense. I have to say that having lived with digital volume controls for the last seven years, it was nice to be able to raise or lower the volume just that last little bit.

I am not going to tell you that there were overwhelming improvements to what I refer to as my daily driver of a system. The setup of the room and the equipment that we have there are an excellent sounding combination. I think the simplification of the signal path between the source and the transducer is always a good thing. If the room and speaker combination are properly matched, the source components and the switching become even more critical.

On the Bench (JEJ)

The measured frequency response using the XLR connections is flatter than with the unbalanced RCA input (graphs shown below), but both are within spec, at least as high as we could measure.

Using XLR and a 1 kHz input sine wave signal, and adjusting to have the same output levels, the measured THD was higher with XLR than it was with RCA, but the noise floor was about the same.

With 11 kHz and 12 kHz input signals, there appeared to be more IMD with XLR than with RCA. Notice the 1 kHz peak (12 kHz minus 11 kHz = 1 kHz) in the XLR graph vs. the smaller one in the RCA graph.

With this preamplifier, I would suggest using the RCA input rather than XLR.


The InnerSound preamp certainly provides a clean signal path, and its performance is excellent for both output level control and switching. There was not any audible crosstalk or induced noise with no input supplied at full output. This is a well made high performance stereo preamp. It made me wish that I had transports with the D to A conversion that it deserved. If you're looking for a device at this price point, which is high, but not absurd given the performance, it would be worth the time to listen to this piece in your system. The only shortcomings that were apparent were the result of my aged analogue sources and the quality of the D to A conversion at that point.

I used the following equipment while evaluating the InnerSound Remote Control Preamp:

Marantz LV 520
Toshiba SD-2108
B&K ST-60
B&K ST-140
B&K AVR 202
Triad In- Room Gold Loud Speakers
Vampire Wire Continuous Cast Copper Interconnects
Canare' 4 S 11 Speaker Cable
Innovative Technology Transient Suppression
Radio Shack SPL Meter

- Brett Johnson -

Manufacturer Response:

I have a couple of comments you might find useful. First, the unit is light because the chassis is made to the highest possible quality standards. This means that the chassis is 100% machined and anodized aluminum. As a result, it is light. This is an advantage when it comes to placing it on another component that might be unable to handle a heavy preamp.

The low frequency response of the unit is limited by the input coupling capacitor. Like most SS equipment today, the preamp is a differential unit that is flat to DC. So the bass roll-off is defined by the coupling cap. We have recently changed this to a larger value so the bass roll-off doesn't begin until below 20 Hz. Of course, the unit you tested didn't have enough bass roll-off to be audible in the audio range, but it is good to know that all future units will have flat bass response to 20 Hz.

Roger Sanders
InnerSound, Inc.

Related to the article above, we recommend the following:

Nature of Equipment Reviews
What we Hear High Fidelity
Equalizers Accuracy, Distortion, and the Audiophile

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