DAC Listening Experiment

I am in a somewhat unique situation to test whether I can detect differences between digital-to analog internal chips on 2 different components. I'm requesting input on my little experiment from all the knowledgeable and interested Audiogon members prior to beginning. Before I explain my test, I wanted to give you a little background on my system since some of my older components have required replacing (streak of bad luck):

1. About a year sgo, my B&K Reference 20 surround processor conked out on me. I replaced this with a used Parasound AVC2500 processor (not the 2500U version which is newer)that I bought on Ebay for the bargain price of $130 plus shipping. It did not include the setup mic or remote but this thing retailed for $3,500 when new back in about 1990. No HDMI, of course, but I knew I could work around this.

2. Also about a year ago, my Sony DVP-S7700 DVD player's video section quit working but the CD section still worked. This model has 2 laser pickups, one for video and 1 for audio, so I thought the video laser must have gone out. I used this for CD playback only ever since. However, I just bought a used model on Ebay for $60 that arrived yesterday. It's in excellent condition and the seller stated all functions work well, although I haven't hooked it up yet to confirm this.

3. The last of my ancient pieces of equipment to fail me was my Aragon 4004 amp (original version circa 1989, not the newer MKII version). The right channel went out in December of 2012. The power supply caps had leaked and I was quoted $300-500 for replacing all the caps. I decided to try out class d, instead, and bought a ClassD Audio SDS-440SC amp that has 440 watts@ 4 ohms. I've been using this since February of this year and am thrilled with it.

So, after all of this, here is my current system:

Sony 7700 dvd/cd player
Parasound surround processor
VTL 2.5 tubed analog preamp with ht pass through
ClassD Audio amp
Magnepan 2.7qr spkrs
Kinergistics subwoofer (used as a LFE spkr for ht and sometimes with 2-channel music hooked up via a Paradigm subwoofer controller)

My current opinions on the performance of this system is 'good' for 2-channel and 'very good' for ht.

Now, here is the experiment I need your input on:

Comparing the sound of the Sony's internal DACs to the Parasound's internal DAC chips to determine which sound better to me. My thought is I could isolate which dacs are being used during playback by the following:

Sony dacs: run rca cables from the Sony's left and right analog audio outputs to the 'CD' left and right analog audio inputs on the VTL preamp. By selecting 'CD' on the input selector of the VTL, a cd would be using the Sony's internal dacs to convert the cd's digital stream to analog signals.

Parasound dacs: run a toslink cable from the optical digital output on the Sony to the optical digital input on the Parasound. Run rca cables from the Parasound's left and right analog audio outputs to the left and right analog 'HT'inputs on the VTL. By selecting 'HT Passthru' on the VTL, a cd would be using the Parasound's dacs to convert the digital stream coming from the Sony via Toslink cable to analog signals that are then sent to the VTL's 'HT' main left and right inputs.

If I setup my system as described above, my thinking is I could just play a familiar cd and, as long as the VTL's input selector is set to 'CD', I could just toggle between HT passthru settings (ht in or out) and compare the Sony dacs to the Parasound dacs. Of course, I would need to make sure that both volumes are matched.

So, what do you guys and gals think of my little experiment. Please feel free to punch holes in my 'double naught' ciphering. I won't begin this test until I get feedback and make any necessary adjustments. I just want to congadulate all those who made it through this thread to this point. Sorry for the length of my tome, but it was harder to put into words than I originally thought. Looking forward to your thoughts. I will definitely post my impressions if I can configure this experiment properly and if anyone gives a hoot.

Thanks all.

Tim- there is one variable that you have not accounted for- the effect of the toslink connection. so you will actually be comparing the sony dac to the parasound dac + toslink cable. That is, of course, assuming that the analog cables in your experiment are all the same.
Hi Swamp!

I've missed you. How's old man Flanders? Are you still living in What's That Smell, Louisiana? Still drinking your Wild Turkey with a bucket of crawfish down at the Pink Croc? Did NASA ever reimburse you for your underpants they rocketed into outer-space?

You make a good point on your post above about the Toslink cable. But it's just a regular Toslink cable that contains no snake oil.

Also, the connection from the Sony goes through 2 preamps to test the Parasound's dacs (even though the 1st leg is a very clean digital connection) while the connection only goes through one preamp testing the Sony's dacs. This may level the playing field a bit.

But if the 2 preamp setup sounds better than the one preamp setup, I might go with it anyway. Or, I might look into separate dacs, including tubed versions, that use the same or similar dac chips.

I will use identical 6ft rca cable pairs (Acoustic Research). Not great cables but good for control in an experiment since they're the same.

I can't be accused of bias toward one dac chip manufacturer since I have no idea which dacs are used in either component.

Nice blogging with you, Swamp-pants, don't be a stranger.

Me, too.
Just fine.
Nope, I've moved to East Bumf-k, West Va.
My bro-in-law's got me hooked on Jefferson's.
I didn't mind when they sent them up, but when they put them in the Smithsonian w my roller skates, I was a mite t'ed off.
Love you, too.
The Muddy one.
Yes, I remember those rollerblades you always tooled around on with just your speedo.

Sorry, I called your speedo underpants on my earlier post. I'm glad to hear your speedo made it to the Smithsonian but, I'm a little confused, wasn't that speedo classified as a WMD (weapon of mass destruction) by the CDC and Department of Defense? Your story is all coming back to me now.

I was also wondering if anyone knew, or knew how to find out, which dac chips were used in the Sony DVP-S7700 and Parasound AVC2500. I think the Parasound used Cirrus Crystal dac chips but I'm not sure which model#. I have no idea on the Sony dac chips.

Any help on this is greatly appreciated.