A few questions about DAC basics

Thanks for the responses. Sorry if these questions are pretty basic.

So, it sounds like if I want to have a better two channel signal for playing regular CD's the DAC needs analog outputs.

If I understand correctly, if I also want to be able to preserve using the DVD for home theatre the DAC will also need a digital out that goes to the digital input on the receiver. The DAC is that case does nothing to the signal except serve as a pass through to the receiver?

If that is accurate then that is pretty simple. I will need a DAC that has both analog and digital outputs. I guess I would also prefer it has both toslink and coax inputs as this new glass toslink I am trying has been a wonderful upgrade.

Oh, is there a noticebale difference in general in the upsampling capability from 96 to higher (132, 192)?
My CD/DVD player does output a 24/96 signal in DD and DTS. I don't know what it does to the signal in playing regular CD's which are 16/44; I am guessing it just defaults to the source signal level in that case.

Any suggestions on a decent DCA that has the needed features is welcome. I see several used ones on Audiogon that are in the price range of 3-500$. I will, of course, read other threads for similar requests for buying suggestions.

Thanks again.

Ok. I think the first step is to talk to Denon about the following two basic questions and hope I get a tech that knows what he/she is doing:

1) What exactly happens to a signal via regular analog inputs into the Denon CD or DVD analog inputs for example, when playing two channel Stereo mode.
The manual is unclear but seems to imply that minimal processing is occurring to any signal that is not Dolby Digital or DTS. Although "Stereo" is technically a surround mode, none of the DSP effects are available, nor is the LFE adjustment to the sub available when the signal is non DD, or DTS. In fact the manual later then excludes the Stereo mode as a surround mode when listing them.

The manual is not as explanatory as it could be. It DOES then go on to state that ONLY the Stereo Mode can be used when playing PCM signals with a sampling frequency of 96kHz.
I guess my related question is what would happen to a DAC signal at 24/96 inputted (manual is unclear as to whether this is an analog or digital signal input) when using Stereo mode; and what does the Denon do to the bass or sub pre out settings in that case.

Here are a summary of the Denon specs from their website:

AVR-1801
Dolby Digital & DTS A/V Receiver • 24 bit DSP processor • 5 equal power amplifier channels • 70 watts per channel into 8 ohms, <.08%THD, 20Hz - 20 kHz • Discrete power amplifier stage • 5 Channel Stereo • Personal Memory Plus • Virtual Surround (for use with 2 speakers) • 24 bit, 96 kHz DACs • 24 bit, 96 kHz digital interface receiver • 24 bit, 96 kHz stereo PCM digital playback • Speaker A/B (front) selector • 6 Channel External Input (for DVD-Audio) with wideband (100 kHz) frequency response • Addressable digital inputs, 2 optical, 1 coaxial • "S" & composite video switching • Banana plug compatible speaker terminals (L, R, C) • Pre-amp outputs (L, R, C, Sub) • Preprogrammed remote control features TV, VCR, DVD codes from other manufacturers

I can set the speakers to "Small" (80Hz cutoff) or "Large" (full range) in Stereo mode, and do some adjustment of the Sub pre out signal, but that is also a bit unclear. I think that possibly if the fronts are set to "Small", then the sub pre out handles anything below 80hz, but I could be wrong about the bass management in this case. I can also set the fronts and the sub to both accept a full range signal and use the crossover on the sub to cut out frequencies above a sub crossover selected frequency. My sub crossover goes from 50-180 hz. It is a pretty fast sub designed for music.
The Denon manual actually suggests doing it this way-running a full range signal to both the fronts and the sub and using the sub crossover to blend with the fronts based upon the range of the fronts. My fronts are rated down to 45 hz.

2) Find out exactly how this EXT IN grouping of RCA ins works. The manual upon further reading clearly states that all surround processing is bypassed and implies that the sub/bass management is handled by supposedly routing the signal to the standard pre-out as I have stated, if it is used, but the valid questions raised here is how to get a sub in signal into that EXT In sub in line level jack without degrading the signal or compromising the FR and FL signals. The speaker level inputs to the sub has some promise here. This could be a way to go.

I could use splitters to combine the FR and FL signals to mono to the EXT IN Sub in, while also running the separate FR and FL signals to their respective inputs. 3 splitters total. (Yuck).
Curiously, I have a Pro Audio Mackie Mixer in my Recording Studio setup and this is actually the way they tell you is preferred to run a line level signal to the sub (use a splitter to combine the full range R and L channels and then to the RCA line input to the sub, and then use the sub crossover.
This is not quite the same thing as a DAC signal split out as stated by you guys, and is probably not a good idea.

I will keep you posted as to what Denon has to say and go from there. Yes, my head is spinning.
Maybe another option is that this urge to get better sound will pass. :>

Mrowlands - Thanks for the response.

Good suggestion about using both the digital coax out and the optical out from the CD/DVD player to different "destinations" as this would not limit my choices to having to find a DAC with digital out for pass through to the Denon.

I have never used a digital coax, but I know there are many well regarded reasonably priced ones out there. I just switched to this glass toslink from a plastic one and the change was very significant.

I have had my friend also recommend finding a used Perp Tech unit. I will read up on them.

Thanks guys. I am learning a lot.
I may give Denon a call to confirm the info in the manual.

Mrowlands- I left out what it said about the sub jack in the EXT IN group of RCA in jacks. It has a SUB IN and this signal is routed to the regular RCA pre out that I have my sub in now. I guess I would put the sub conncetor into the EXT IN Sub In jack and it would route it correctly when listening to two channel.

One more dumb question. It has dawned on me from the discussion here that my signal out of the Pioneer Elite DVD/CD D/A is then being reprocessed by the surround circuitry. AM I correct in assuming that I could route the RCA outs from the Pioneer Elite ot the EXT IN jacks and bypass the Denon surround stuff? I could leave the toslink in place for when I wanted to do HT.
My guess is that the Pioneer DCA is better than what is in my Denon. Here is what the Pioner manaul states about the transport and the DAC:

CD Mode for Full CD Changer Functions & Video Off
High Speed Loading and Resume
10-bit Video Signal DAC 96KHz/24-bit Audio DAC
Hi-Bit Legato Link Conversion
Dual User Memories
Twin-Wave Laser Pickup for CD / Video CD / CD-R playback
Viterbi Error Correction for Superior Reading Accuracy

Other than pushing a button and maybe having to switch the sub cable this might be better two channle than now even without a DAC.

I think am going to try autditon a DAC if the EXT IN thing will work. I will call Denon.

Thanks to all.

Mrowland -

Hmmmm..... You are right, if I use a DAC (or even just the Pioneer DVD/CD analogs) into the EXT IN FL and FR inputs I am missing a signal to the sub.

I wonder if an RCA Y splitter was used to the SUB IN from one of the FR or FL channels to the SUB IN in the EXT IN group if that would work?
This is how the EXT IN RCA group looks:

O O O
FL C FR

O O O
SL Sub SR

The Denon manual seems to imply that the SUB IN jack in the EXT IN group is routed internally to the regular RCA Sub preout jack which is what I am using for the sub now. If I used a splitter the full signal would then be sent to the Sub and it's built in crossover could be used.
The sub itself (ACI Titan) has three line level inputs (L/C/R), but I am guessing that is not what you mean by "That's why you'd need a sub with 2 sets of inputs".
I can get a speaker level input adapter for the sub from ACI, but have never used that before.

How do people using a DAC get a sub signal to their sub?
Is this why Mraybeck has suggested a real stereo preamp above?

You guys have been great.
Let me try and digest this a bit and I will post later today.
Thanks!

Talked to Denon and a Tech named Tony who was very helpful.
This unit does have analog bypass through the EXT IN inputs.
He confirmed that anything through the regular inputs would go through the Denon circuitry.

His solutions to the subwoofer were:

1) Get a DAC with two sets of analog outputs and run one set to the FL/FR of the EXT IN, and take the other set and use a Y cable and run it into the EXT sub in input. He stated that the DAC must have two discrete buffered analog out pairs.

2) Use the analog outs of the DAC for the FR/FL and if the Pioneer had two sets of discrete buffered analog outputs (which it does) then run a separate signal to the EXT IN sub input from the Pioneer rather than the DAC. He stated that their may be some timing issues with this, but they would probably not be noticeable at the low frequencies. Only trying it out would tell if that would work.

3) You could just not use the sub for two channel since the monitors went down to 45 hz depending on what kind of music I generally listenend to.

Of course the speaker level connections for the sub should also work which has been suggested by this forum.

Thanks for all of the help.

Small update. Ran the Pioneer through the EXT INs to bypass the Denon. Sub was not hooked up.
Did A/B for several minutes on a CD that I know well (Foreplay-Heartfelt).

Mrowlands - You were right, it sounded better. The bass was definitely extended and tighter, and the mids/highs had a bit more presence. The overall soundstage also had more depth.
This was using some cheap RCA cables I had laying around.

Well, no matter what I do, the EXT INs are going to get used somehow for two channel listening. I have been convinced about bypassing the Denon circuitry for two channel. I had no idea.

Thanks again.

Mraybeck - Thanks for the info on your experience. I am trying to be careful about which route to go. I appreciate the info. I had been wondering what role the Denon plays with any signal that comes into it-digital or analog.
Obviously to do the DSP junk (which I do not use) it has to be grabbing the signal and processing it. For Home Theatre one wants it to handle the signal in 5.1, but for stereo I would just as soon it left it alone and let the D/A from the Pioneer DVD/CD handle the duties.
Getting the Parasound to bypass the Denon power amp for the fronts made a major difference.

I think I understand what you are saying about the input signal from a DAC being then "reprocessed" through the Denon surround circuitry.Probably defeats the purpose.

What about this from the Denon manual: ????????

Playback using the external input (EXT. IN) jacks
"Set the external input (EXT IN) mode"
Once this is selected, the input signals connected to the FR,FL,C,SL, and SR channels of the EXT IN jacks are output directly to the fronts,center,and surround speaker systems without passing through the surround circuitry"

Is this what you mean by an analog bypass circuit?

As far as the toslink, I was using a cheap plastic toslink.
I didn't know any better. I then did some reading here on Audiogon and just got the SOUND Professionals Glass Toslink.
Major difference is sound clarity, depth, space, and actual volume of the signal. I do, however, want to try a decent coax and compare. Most people smarter than me seem to prefer a coax to a toslink.

Let me know if this EXT In thing has any merit. I never really noticed it, or thought about it until lately. Supposedly this Denon can use a totally different processor if one wants to do so.

I have thought about a separate preamp, but where do the speaker wires go for the fronts. They are presently connected to the Parasound. I am a little fuzzy on this point. This si the discussion that my forend and I got started on that led to him stating to try a DAC rather than try and configure a preamp with my existing system. He maybe assumed that I has analog bypass (which I might if the EXT IN thing works as I read it).

Thanks.