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Hey there BrainFood.
Thanks for the information.
5.6v on XLR and 2.8v on RCA is one heck of a lot. And, that's averaged.
There's usually a manufacturing tolerance of +/- .1v or .2v on stated
outputs. So I could easily see some X20's pushing 5.8v.
No wonder my poor old Pathos amps were struggling.
It makes no sense to me why they've pushed the output up so high, and would
love to hear from the company about the reason behind this particular decision.
The main reason seems to me quite obvious: that the X20U can also be used as a preamplifier (see more below - also, not that it may be its optimal use, but it is intended at least to function as such) and to make it easier to match it with the inputs of various amps and preamps. This is a point where the X20 is clearly superior to other DACs.
Whereas on DACs like the X-Sabre you do not have volume control, and thus are known to saturate the input of some preamps, the X20 is better because you can attenuate in the digital domain, and since it is internally computing with a lot of headroom (48 bit DSP, with a claimed resolution of up to 32 bit in the DACs) I would definitely not worry at all about signal loss. Have a look at the expected input of your preamp, and reduce the the max output of the DAC to match that. Example, the Abrahamsen V30 preamp is probably ideally matched to the Abrahamsen DAC that has 3.2Vrms on the balanced output, so I configured the X20 with a -5Db attenuation. 5.6*2^(-5/6)=3.142 Vrms and it indeed seems to sound at its best there.
As we discussed in other posts, up to -40Db there should be no loss of quality (and at that level, it would be probably too soft anyway)
Luckily, the X20 sounds great, and I can't detect any quality loss by using the
unit at -9db. I tried a borrowed pair of Rothwell -10db XLR attenuators, and
thought they veiled the sound a fraction compared to simply lowering the X20's
output.
Again, to use it without a preamp! I tried to connect the X20U directly to my Abrahamsen V40 power amp. Listening at -25Db with gain = 0Db the volume level was the same as with the amp. The soundstage was slightly larger and deeper (as to be expected since there are less active components for both channels, relatively close to each other, that may thus reduce channel separation) but the sound was more fatiguing and slightly too bright - less mellow in general. Detail was comparable (this tells a LOT about the quality of that preamp). I know some types of audiophile that would prefer it without preamp, I belong to those that prefer the configuration WITH the preamp. Chacun à son gout.
If you are listening in a much larger room, with less sensitive speakers, then the gain levels of +6Db or +12Db may come out useful (say you just connect the DAC with longer balanced connections to mono blocks close to the speakers).
Luckily, the X20 sounds great, and I can't detect any quality loss by using the
unit at -9db. I tried a borrowed pair of Rothwell -10db XLR attenuators, and
thought they veiled the sound a fraction compared to simply lowering the X20's
output.
This confirms my suspicion that adding attenuating cables can deteriorate the sound.
Set the volume of the DAC to -9Db and be happy. I know (as a professional mathematician) that mathematics for some reason does not explain everything in audio, but I would really not worry at all because of such a relatively minor level of attenuation in the digital domain on a ES9018 based DAC.
Cheers
