Originally Posted by sillysally
But don't forget you are still doing a A/D conversion with the Realisers DAC.
Yes, because I don't have the HDMI option. I'm thus still using the Realiser's analog inputs for anything fed to it, which involves its A/D conversion.
But my SRM-007tII has THREE inputs, so I've been able to set up three easy comparisons of various sources feeding the amp, simply by pushing the INPUT button on the amp:
(1) RCA output of DAC -> DBX EQ -> SRM-007 INPUT1
(2) RCA headphone output of Realiser -> SRM-007 INPUT2
(3) XLR output of DAC -> SRM-007 INPUT3
Furthermore, the DBX EQ has TWO L/R-stereo line inputs, which I've set up as follows to facilitate comparisons between its two sources, simply by pushing the INPUT button on the DBX EQ:
(1) RCA output of DAC -> DBX EQ INPUT1
(2) main RCA output of Realiser (in analog bypass mode) -> DBX EQ INPUT2
Since the Realiser's analog bypass mode sends whatever it receives on its analog inputs direct to its analog outputs, and since the Realiser's analog inputs are fed directly from the analog preamp-outputs of the AVR, I'm thus able to compare whatever is feeding the AVR (digital via HDMI or analog via L/R-stereo) with whatever is feeding the DAC (digital optical from Realiser or digital coax from Oppo), listened to in a variety of paths.
The first thing I did was use a familiar single CD-audio source into the DAC to adjust my DBX EQ (INPUT1) to create a preset whose gain and tone produced a match between the DAC/EQ/AMP all-RCA path and the pure DAC/AMP XLR path. This at least allowed me to be not distracted and fooled by different "loudness and tone" into deciding which one sounded better. They sounded identical.
Now the DAC has two digital inputs that are usable for me: (1) optical, which is fed from the optical output of the Realiser, and (2) coax, which is fed from the coax output of my Oppo-BDP83 player (which I have set to put out 2-channel LPCM/192 over optical/coax for CD audio, as well as multi-channel LPCM/192 over HDMI fed to my Yamaha AVR for BluRay movie audio).
Furthermore, the analog inputs to the Realiser come from the preamp-outputs of the Yamaha AVR. So depending on what source is selected on the AVR, that's what is fed to the Realiser and thus comes out both its optical digital (to DAC) and analog (headphone) ouputs.
Thus I'm able to compare LOTS of different things, by choosing (a) the input to the SRM-007, (b) the input to the DAC, and (c) the input to the AVR. And I won't be "fooled" by any wrong setup in the DBX EQ.
Finally, the Oppo's analog L/R-stereo output are also fed to the Yamaha AVR (for the "CD" input). So I can even compare an all-analog path from Oppo analog -> AVR (CD) analog -> Realiser (OFF, thus analog bypass mode) -> DBX EQ INPUT2 -> SRM-007 INPUT1, and by setting the DBX EQ to "flat" I'm really listing to a pure old-fashioned no EQ analog CD-audio via headphones and with "no outside interference".
So I can really compare anything, fairly and objectively, using my home-grown "patch panel" of input selections on the various components.
Most importantly I can compare the RCA analog headphone output of the Realiser (D/A from its built-in DAC) to the analog output (both XLR and RCA) of the external DAC (fed by digital optical output from Realiser) for the identical 2-channel or multi-channel AVR preamp-output analog source that fed the Realiser's main analog inputs.
I can also compare the three simultaneous outputs of the Oppo, (a) 2-channel analog stereo, (b) digital coax LPCM to DAC for 2-channel CD audio, (c) HDMI LPCM to AVR for 2-channel CD audio as well as multi-channel BDMV.
I can also compare the RCA output of the DAC vs. the XLR output of the DAC.
I can also compare 2-channel CD audio coming through the Realiser (and its various PRIR's) vs. the same 2-channel CD audio coming directly from Oppo -> DAC -> SRM-007 (both XLR and RCA) and bypassing the Realiser.
And... subjectively, DAC-XLR beats "equalized" DAC-RCA, but only by a very small amount and maybe even that's unfair.
It's unfair to compare pure XLR to pure "unequalized" RCA, because the RCA output level from the DAC is only 1/2 that of XLR and the "loudness" difference makes comparison effectively impossible. So once they've been equalized to sound the same (both tone and level), they really do sound the same! So how can a comparison now be meaningful?
I suppose I could create one more EQ preset, which was "flat" but simply added gain across all 14 frequency bands equally (or maybe slightly skewed?). Theoretically this would simply make the RCA output of the DAC "just louder" and reflect no tonal differences, so that only the tonal characteristics of RCA could be compared to the tonal characteristics of XLR as they would both sound equally "loud". Might work.
And... subjectively, external DAC is a very small improvement over the built-in DAC of the Realiser. It's certainly nothing very very noticeable, if it's there at all.
This is not a condemnation of my Audio-GD NFB9 DAC. It is simply a confirmation that the built-in DAC in the Realiser is excellent as well.
Most interestingly, I've found that I no longer seem to want or need the "tone control" results of my DBX EQ (from an all-RCA path), now that I have an XLR option feeding the SRM-007 (or my other SRM-T1S).
Although it seems like an unfair and invalid comparison and maybe even an incorrect statement, but there seems to be a tonal difference (i.e. improvement) using XLR into the amp vs. RCA. Once I get all the various level controls adjusted properly so that I hear my familiar listening level in my headphones (since XLR is twice that of RCA), I find that I can easily listen to the XLR input (which has no EQ involved) and not crave tone control.
More remarkably, assorted non-AIX PRIR's on the Realiser now sound "better" when I listen using the external DAC and its XLR outputs (and thus no tone control), than when I had used the Realiser's DAC and DBX EQ. Maybe it was the EQ preset that could have and should have been improved.
Very surprising. Very interesting.
Maybe it will all settle down after I do much more listening via my DAC, as it's finally reaching the end of its 1-week burn-in and I can now return to normal viewing/listening habits through Realiser and headphones.