Integrated Amplifiers

ONIX H6550 Integrated Tube Amplifier


The Design

Unpacking all AV123 products is an event in itself; you become part of the club once you place those white gloves on your hands (really meant to aid in handling delicate tubes that don't appreciate oily fingers, but don't panic, we all have them). Lifting the 74 pound unit is a challenge, but don't despair, quite worth the effort.

Whereas the SP3 is glossy gray, the H6550 is liquid piano black. Gone from the design of the H6550 are those curved elements that gave the SP3 unusual styling. The newer version is larger and much boxier, almost shouting how much more serious it wants to be taken.

But oh that finish is stunning!



  • Tubes: Two 12AX7, Four 6SN7, Four
  • THD+N: 1%
  • Input Impedance: 250 kOhms
  • S/N: 90 dB
  • Dimensions: 7.4" H x 17" W x 15" D
  • Weight: 74 Pounds
  • MSRP (USA): $1,995


Onix H6550 Integrated Amplifier Front Left Product Reviews The H6550 sits on three sturdy legs, giving good isolation from its stand.

On the face of the H6550 you'll find three control knobs. A centered volume control is flanked by power on/off and an input selection knob. With four RCA input options, ONIX labels them Tape/CD/Aux/Tuner.

Turntables have become popular again, very much like vacuum tube amplifiers themselves. I happen to plug my iPod into one of those inputs, but that experience comes later.

The H6550 is a class A/B push-pull design, which means among other things, it idles in a lower current, thereby allowing it to produce more power under demand.

On the rear you'll find four sets of RCA jacks for those inputs, sturdy gold-plated right and left speaker binding posts for both 4 and 8 ohm speakers, a removable power cord, and a fuse replacement location.

The sides have small holes for a small screwdriver, which is for bias adjustment. ONIX ships the tubes in place and with the bias properly set (2 volts).

The main set of tubes is covered by a removable cage cover, easily popped off for tube replacement or just to watch the tubes glow. Keep it on if you have a cat or small children, they run quite hot. Take the cage off if you like to see the tube filaments glowing.

The high quality compliment of tubes includes 10 (similar in quantity to the SP3), and although they share only one tube type, a pair of common preamp high gain 12AX7s, the similarities end there. Completing the array of tubes includes four medium gain preamp 6SN7s and the power-generating 6550s, each channel having a pair. The 6550 output tubes are known for their reliability and produce an impressive 50 watts per channel.

Having a look "under the hood" you'll discover craftsmanship and quality, and neatness counts. Notice that probably 95% of the circuit is hard wired, rather than PC boards. This is one of the features that tube lovers love.


Onix H6550 Integrated Amplifier Inside Chassis



When I reviewed the SP3, I was fortunate that the excellent XCD-88 CD player was sent along with it; my regret is I didn't have the upgraded CD-3 CD player from ONIX to partner up with the H6550.

For those interested, I used primarily for review my reference Krix Symphonix speakers, a Denon DVD-2910, and Ethereal cables throughout. I did swap the stock power cord with a new Wireworld "5-squared" unit. This setup is right in line with the sub-$2k ONIX. I've had the H6550 so long (thank you, Mark), that I was able to review a McCormack universal player and a pair of unique Onkyo speakers (the D-TK10) all with the Melody.

Onix H6550 Integrated Amplifier Binding Posts Product ReviewsThe Sound

Let me get the iPod experience out of the way first. You purists don't need to chastise me for the experiment, I couldn't help myself, I needed to give it a try and I'm glad I did.

To my absolute surprise, the H6550 delivered such superb music from the iPod as a source that I left it plugged in for most of my background listening. I certainly won't pretend to compare the MP3 player with a quality CD player: bass was somewhat lacking, but acceptable, treble was pleasant especially with vocals, and the highs lacked some detail but were reasonably defined. I give full credit to the ONIX.