Review: CODA S5.5 Class A Power Amp

My initial foray into a pure Class A power amp was a First Watt Aleph J amp clone DIY build that I bought from a builder. These amps are rated at 25WPC, and are, of course, a Nelson Pass design. I've had that amp about a year-and-a-half, and have thoroughly enjoyed it. But, at high volumes, I felt that a plateau was reached, and any additional gain started to get lost in the mix.

So, I started considering a higher output pure Class A amp. Naturally, Pass Labs amps kept coming up first and foremost. But, I also ran across the CODA S5.5 while browsing reviews. Many reviewers, with more exposure than me, preferred the 5.5 over Pass Labs. Color me interested.
Full disclosure: I already had a CODA 06x phono preamp, so I'm not totally new to the brand.

I eventually ordered a brand-new S5.5 from CODA. These are built on demand when ordered, and frankly, it took longer than anticipated to receive my unit. A big factor in the delay was my order including a silver face plate. CODA was not satisfied with the silver anodized aluminum face plates being provided by their supplier, so they kept sending them back, and we had to wait for new batches multiple times. Btw, the faceplate is substantially thick, being 3/4" thick across most of the width, and ~1/2" on the edges. It is not a particularly large or heavy amp, at 17.5 X 12.5 X 5.75, and weighing 45lbs.

I finally received my unit a few weeks ago, and have been gathering my thoughts in order to do this little review. I know some forum members here get a woodie about unboxing, so here are a few pics of that process.






Visually, it is a lovely amp with an elegant design, but the amp's topology design also deserves mentioning. One of the more interesting specs about the 5.5 is the current output. It has a maximum output current of 100 amps, which I'm certain qualifies it as a high-current amp. Of course, that max current demand would only be needed in extreme situations. But, that amount of potential current demands respect IMO. Another unique feature is that each channel has 30 output transistors, which are described as having an "extremely wide bandwidth". I honestly don't know the advantages of that, but 30 transistors per side seems unique to me, and I believe the outputs are different than the typical kinds used. Here's a stock pic under the hood, and also a pic of the rear.


CODA does an initial burn-in at their factory on new builds, but they recommend at least another 50 hours of additional burn-in at home before doing critical listening.

As far as the sound, the S5.5 has delivered on what I was seeking, and then some. To reiterate what I mentioned at the outset, I have thoroughly enjoyed my FW Aleph J, and all the Class A goodness it provides. I just wanted more. The 5.5 has all the mid-range lushness and natural timbre of Class A, but I detect a lower noise floor (or lack of a noise floor), that translates as more transparency, spaciousness, and a wider soundstage - literally a foot or more wider on each side than previous amps I've tried with my JM Lab Mezzo Utopia with @VR3 external crossovers. Frankly, I was hoping and expecting those things to be apparent at this price point, but what pleasantly surprised me was an extended linearity at both the low frequencies and high frequencies. The low-end digs deeper with more punch and authority, and the high-end extends further up into the spectrum with more air and detail. My guess is that the high-current nature of the 5.5 provides the low-end power and damping, and the high-end detail is the result of the impressively low SNR of the amp - CODA claims noise "less than 120dB referenced to rated output", and I believe it, based on my listening experience. Overall, there is a liquidity, immediacy, and effortless sound that has lots of headroom to spare.

I could wax on poetic, but don't feel the need. CODA is not a huge brand, and doesn't get a lot of press, but I would recommend keeping them on your list when shopping.