A few questions about DAC basics

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:

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?

Lkdog,
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

Lkdog,

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.

Whew!

Let us know what happens.

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