The new Coda S5.5 amplifier: It's a "Petite Beast"!

 I found the XLR cables to be a poor match to the Coda 

This is such an interesting hobby at times. I found the exact opposite, I recently bought this amp used, and for one day I listened to the S5.5 with XLR from DAC to preamp, and RCA from preamp to Coda. Was okay, but disappointing to be honest, and sounding inferior to my $3000 300B amp- not just the expected midrange but with the bass and high frequency details as well. 

I simply switched the same interconnects around; put the RCA’s between DAC and PRE, and the XLR’s between PRE and S5.5 and this is a completely different amplifier, for the better, and more in line with the glowing accolades described in this thread. Without naming brands the 3 sets of cables going into the amp retail for the same amount as the S5.5. 

With the first setup I wouldn’t buy this amp for $3000, in the second configuration it sounds like a > $10,000 amplifier- and I own the Coda 15.5. 

The EAR 868 pre I am using currently has an output impedance of 600 ohms, so this 10000 XLR/600 = 16 to 1 ratio and for RCA 50000/600 = 83 to 1. The theory states a minimum 10 to 1 ratio for amplifier to preamp impedance, which I have with XLR, but in the case of ARC and others claiming the closer one can get to 20:1 the better, so on paper RCA looks like the way to go, but in my case this is irrelevant. If someone can see some other factor in play, please enlighten me: I was thinking perhaps the RCA’s have never been used on this amp previously so they require a little burning in? Perhaps the EAR is much better with RCA’s? I have no idea. 

I ran this by Doug and he was baffled, the XLR should have a wee-bit better S/N ratio, and be a little (3db) louder, but otherwise he states there should be very little difference. The difference I hear is well beyond this. As I write this it is very early in the morning, so I am currently listening at 49db, and I am getting pristine low level detail and deep rich nuanced bass- this was not the case with RCA’s at 75db.

Just goes to show to get the full picture with a piece of audio equipment you gotta try different permutations, and quick demo’s can be misleading. Yes, this is a wonderful amplifier and I plan to own it for a very long time. 

Thanks for the thread @teajay 

@sim_audio_nerd I threw some NOS Siemens PC88's in the 868 and it definitely improved over the stock Harmonix. I love the inner detail retrieval over excess warmth, but with the astounding high frequency clarity this S5.5 unravels I feel inclined to try some Mullard's, and/or I have a couple of other pre's I will rotate in the system in time and check their synergy. 

@soix Thanks for the comment. Yup, that may have something to do with it. I have a few other cables to play with also which I will experiment with eventually, but will listen as is for a while first. 

 ...but as others have mentioned the speaker inputs are crossed in the back with the left side on the right of the amp and vice versa. 

@npdang 

I think it is easier this way: I have ignored the red and white colors that are on the RCA inputs- looking at the front of the unit, if one puts the right RCA or XLR signal input on the right input, and connects the right speaker cables to the right binding posts all is good.