A few questions about DAC basics

I have been making a few upgrades to my system and a friend suggested that I consider a decent used DAC as a good upgrade. He was not really sure if my CD/DVD player could use a DAC. He has very high end equipment and has separate transport/DAC etc. Guess he hasn't slummed it with off the shelf integrateds for awhile:)

Here is my system:

My system is:
Denon 5 ch DTS receiver (1801)
Parasound 1000 hca amp for the fronts only
RBH Sound 61SE fronts
RBH 661SE Center
Polk Audio S6’s for rears
ACI Titan Sub
Pioneer Elite DVD/CD player DV-C36
DH Labs T14 silversonic speaker wire
Tekline TL 2000 RCA interconnect from the Denon L/R preouts to the Parasound amp
Glass Toslink digital cable from Pioneer to Denon

My first question is can I add a DAC to this system?
I am assuming that the Pioneer d/a converter is what I am using now when I play CD's.
I have coax, optical and regular RCA outputs on the Pioneer.
Presently using a Glass Toslink to the optical in on the Denon. The Denon has two optical ins, a digital coax in, and several RCA analog pairs in, as well as additional Ext. in for 6.1.

My second question is more like several and I apologize if it is too simplistic. From reading these forums it seems that an external DAC is connected from a digital output from a CD or DVD player and then has outputs that go into the preamp, or in my case the Denon DTS receiver. Does the DAC connect to the preamp via analog in or digital in to the receiver?

I am also assuming that the DAC handles the digital signal in such a way as to improve or expand it? I read stuff about upsampling, etc and it sounds very interesting.

Another question I have is what happens when I am playing a DVD? This is where I start to get confused.When I am playing a DVD right now, the Pioneer sends the DTS or Dolby Digital signal to the Denon for processing into 5.1.
Does adding a DAC still allow this process? I mostly listen to music, but still want to watch movies in 5.1 dts or DD sometimes.

Finally, is this a reasonable upgrade for this modest of a system, and do you have any suggestions for around 3-500$ used?

Thanks for your input and patience. I have improved my system quite a bit from the info on these forums and appreciate the expertise here.
"Does the DAC connect to the preamp via analog in or digital in to the receiver?"

Analog in--hence digital-to-analog conversion: signal goes in digital, comes out analog.

"I am also assuming that the DAC handles the digital signal in such a way as to improve or expand it?"

It can sort of, although more normally look at it as it simply does a more accurate job than a lesser dac of converting the bitstream into the analog signal. But you're more or less right.

"Another question I have is what happens when I am playing a DVD?"

I think you'd have to run the digital into the receiver to get the surround, someone may know more there. May need a cable swapper/switcher or you'll have to do it by hand or your DVD should/could have internal DACs and you'll feed all the analog straight to the receiver--DVD owners will know more here. I would imagine this last approach means five or six analog cables running to the receiver from the DVD??
Ok, first of all I want to thank everyone for all the great information I have recieved from Audiogon! This is my first time giving advice so here goes.

Using a Dac with your system should be pretty painless. First make shure the DAC you buy has a digital out. All you have to do is run a cable from the digital out on your DVD to the digital in on your DAC. Then run cables from the analog out on the DAC to the CD input on your reciever. This gives you your upgraded CD signal.

Now for your home theater siginal. Now, from the digital out on the DAC, run a cable to the digital in on your reciever. This will give you the 5.1 signal. The original signal will (or should) pass through your DAC unchanged. Just select CD or DVD on your reciver to get the correct siginal.

As far as DACs in your price range, maybe others can help more than I can. I use Theta, but there are many others out there.

I hope I have helped, if you have any questions call me at 1-631-209-0814.
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.
Your DAC shouldn't need a digital out because you can just leave the Pioneer connected to the Denon via the TosLink and use the digital coax for the DAC. What I'm not sure about is what the DAC would do when you play a surround DVD - early (stereo) DACs put out a terrible sound in that case, so you would have to be careful. You may be able to control which bits go where via setup in the Pioneer.

As in all things, implementation is more important than the technology, but upsamplers can indeed sound "smoother" if your system and hearing are up for it. I'd say a Perpetual Tech P3A would fit your needs.
I must caution you against buying a new DAC for your system. My return to 2-channel audio was through home theater, so I went through a similar process to yours. I enjoyed watching movies, but my primary focus was music, so I wanted to improve my 2-channel (music) performance.
Unfortunately, budget-minded receivers like your Denon AVR-1801 do not have an analog bypass circuit. In other words, your new DAC would output an analog signal which would then go into your receiver. However, the receiver converts all incoming signals back into digital to allow for digital volume control and digital surround processing (DTS, Dolby Digital, etc.) Thus, you are still relying on the DAC in the Denon for the final analog signal that will go to your speakers.
If you are serious about improving your music performance, I would look into a good, used 2-channel pre-amp to use with your Parasound, thereby taking the receiver out of the 2-channel loop. You can then input the DVD player (or new DAC) into the preamp, and connect the preamp to your Parasound, then the speakers. The movie output (via the TOSLINK) will still go to the receiver for processing and then the center and rear channels. I hope I am not confusing you, but you really can have the best of both worlds (with some compromises, of course).
If this is a larger bite than you can chew right now, a simple, cost-effective upgrade would be to buy a good-quality, used coaxial cable to connect your DVD to your receiver. I think you will find an improvement over the TOSLINK.
I realize that the complexity of combined HT/2-channel setup can get confusing, but it can be done with decent results. These are some of the lessons I learned (the hard way) when I was in your shoes. I have since seen the light, and have whole-heartedly converted to the purity and resolution of 2-channel! Can I get a witness? AMEN!
Enjoy your system, and remember - HAVE FUN. Good luck.
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.
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).


The EXT IN is perfect, except that if you are using the Sub out from the Denon it may be useless when using the external DAC. I have the same situation with my bottom of the line Onkyo HT receiver, but I find that the music is so much better sounding through my Polk RT25i's with all processing off that the lack of really low bass is acceptable. But then again I have a separate substantial 2 channel system to fall back on!

The only subs that I know of that can be hooked up simultaneously with 2 channels (in the case of your EXT mode) and an LFE (subwoofer) channel are some of the REL subs (e.g. Storm III). Anyone else?

Good luck.
That does sound promising, that passage in your owner's manual. I tried to get your manual and the spec's from the Denon website, but I was unable to do so. I do not know for sure if your particular model does have the analog bypass or not. I'm sorry if I am confusing matters. The Denon receiver that I previously owned (one generation earlier), did convert all incoming signals to digital. I was told by a very knowledgeable local dealer that this is commonly done in entry-level receivers because designing a volume control in the digital domain is much cheaper than a good, quiet analog control.
As far as integrating a preamp, you would still have the receiver power your center and rear channels. However, you connect the FR and FL preouts on the receiver to a R and L line level input on the preamp. The preamp then sends to amp, and from the Parasound to the speakers. With this arrangement, the preamp needs to be on and set to a reference volume level when calibrating for 5.1 channel audio.
I did this exact same upgrade 3 yrs ago, and the improvement was not subtle for 2-channel (even given the fact that the preamp section of my Nakamichi receiver was actually pretty decent).
Check your owner's manual - you may have a block diagram of the signal path in it.
Good Luck,
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.
It's a good idea to try the analog outs from the Pioneer. Regarding the subwoofer, an external DAC like the P3A will not have a subwoofer out, so I'm not sure what you're saying there. You will only be using the FL and FR inputs on the Denon. So the only way to get a signal to the sub is to route the full range left and right channels to the sub, either before the power amp or after it depending on the sub, and use its built in crossover. That's why you'd need a sub with 2 sets of inputs. Either that, or if you want to boogie with some really low bass, you can always switch back to the digital input on the Denon. But I have a feeling that your system will have a much better soundstage without the processing, so try the Pioneer's analog outputs to see what you think.
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:



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?

I do feel that getting a dedicated 2-channel preamp will be a significant upgrade in your system. However, even with a preamp, you will still need either a speaker-level input on your ACI (like the RELs), or use line-level input from a splitter (probably will degrade 2-channel sound) or route the entire line-level signal to the sub to use its crossover, and then from the line out of the sub to the amp. This last method also has its drawbacks as you will be running your entire audio signal through another 6+ feet of cabling. This is why speaker-level input is generally preferred for 2-channel audio.
If you are currently using the RCA sub preout for music listening, then I would be willing to bet that your Denon is, in fact, redigitizing your analog signal. The LFE circuitry is done in the digital domain, and I truly doubt that your receiver has a good analog crossover. If you really want to maximize your system for 2-channel and wish to keep the sub, I would get the speaker-level input adapters from ACI. Just my .02

Nice idea, but there's another problem in addition to the degradation mentioned by Mraybeck. When using the EXT inputs, you'll be running a full range signal to the front speakers, so the crossover setting in the sub that works well this way will not work if you have the Denon set for "small" front speakers! However, as I've said before, my low end Onkyo sigificantly degrades the sound when ANY processing is used (this includes using the crossover via setting the speakers to "small"), so I just leave them full range. The drawback here is that you're wasting power and possibly muddying up the midrange by trying to pump the low frequencies into the small speakers, but life is full of compromises.

By the way, trust me that it won't work very well splitting only one of the channels into the Denon's subwoofer input, because music mixes are too varied (yes, I tried it once). Also, I don't like the idea of combining the left and right because I don't think the output buffer of the DAC would be happy with that.

Many people have had this same problem, so you might do searches here and at the AudioAsylum.com. Many people have tried a separate preamp as per Mraybeck, but it can be a hassle to match the volume of all channels, especially at different volumes.

There are 3 main ways to achieve the use of a sub in your situation.

1) Get a separate 2 channel system. Don't laugh, it's been done by others than your's truly.

2) Get 2 subs. One is hooked up to the LFE channel (you can use the HT receiver's built-in crossovers on everything but the direct pass throughs); the other is hooked up to the preamp outputs (low level) or the amplifier outputs (high level), and its crossover is set to blend with your front speakers running full range.

3) Get 1 sub that has regular left and right channel inputs (low level and or high level) AND an LFE input. As I said earlier, the REL Storm III (and higher models) is the only one that I know of that does this. The crossover must be defeatable on the LFE input if you are using the HT receiver's built-in crossovers, because you will have to set it around 40 Hz for your fronts, but the receiver will probably cross over the fronts at about 80 to 120 Hz.

Just a note. All of this is moot if the HT receiver is able to pull off the low frequencies on the analog pass-throughs. I don't know of any that do this though.


Let us know what happens.
You guys have been great.
Let me try and digest this a bit and I will post later today.
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:

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. :>
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.
Thanks for the update, Lkdog. I am happy to hear that you do, in fact, have an analog bypass circuit. So, if in the future, you wish to add a DAC, you should be able to reap all the benefits. Your little experiment also proves that the DAC in your Pioneer Elite is superior to those in the Denon (not a surprise). Be sure to let us know what you decide to do to integrate the sub and the results.
Happy Listening,
Mark Raybeck
Thanks for the update. Better cables will improve it even further. Have fun!