Thank you both.

I've read about the switchers and at least one reviewer complained of degradation in sound quality. So, I think I've decided. I'm going to buy a pair of quality rca inputs and simply pop out the XLR, put in the rca and visa versa, when switching between systems. It's a bit of b.s. but may be worth it, without signal loss.

This sure has been a learning experience for this old brain of mine! lol

Again, thank you both!

John

The plot thickens!

Man, I appreciate the tech support here and especially from you, Gonk. My feeble mind has a problem digesting all this.

I phoned Anthem tech support and as long as the 990 is in standby (off with the remote), that means the Anthem's auto input selectivity switch will sense an XLR input. This means that if I want to drive the amp, directly, with the ZD, with a pair of single ended cables, then, I have to either pull all five XLR cables or hit the kill switch on the back of the 990 (which given its location, is not easy to do).

If I hit the kill switch, on the back of the 990, will this cause me to lose my setup configurations, over time?

Also, he talked about another, safer solution, using something called "unity gain" (Ok, means zip to me). As I understand him, I'd have the two channel preamp feed the amp through the 990 (meaning the single ended cables from the ZD would attach to the 990 and feed through the XLR cables to the amp). To do this, however, he said that "unity gain" is required. What does this mean? Is this doable?

Or, is he saying the L and R 990 channels would pass through the ZD and then to amp (ZD in the middle)? I'm confused! lol

Any and all information much appreciated and thanks,

John

So if you have any channel connected via XLR, they all have to be? That sounds odd - I'd ask for a clarification on that one. It would certainly be highly inconvenient if someone had any reason to mix channels like we're discussing, not to mention the fact that it seems like they're almost making it harder than it needs to be by tying each channel's auto sensing together into a global behavior.

Killing the power on the rear panel should not cause the 990 to lose its settings, as those settings are in a non-volatile memory (hence the ability to retain settings across power outages - my old Model 950 remembered its identity even when it went 11 days without electricity once).

I could be wrong here, as we are moving beyond my usual territory, but I think that by "unity gain" he means basically a complete bypass of the 990 (including volume control, such that the "gain" or volume applied by the 990 is completely wide open, all the way at maximum). I honestly don't know quite how you'd do that with the 990, but there's definitely not an easily-selected option for this that would preserve the clean signal path you are trying to achieve with the ZD and A5.

Gonk,

I didn't ask that question, but, based on his response, the answer appears to be "yes." He understood precisely what I'm after and knows the amp, its his job; I don't think there's any mistake (reinforced by his idea of using a unity gain method). I could call again, to be sure, but my sense of the conversation was that he knew exactly what he was saying (understood my concern, immediately).

I think your idea of "global behaviour" is correct. While unrelated, directly, it's built so that the five channels share two torroidal transformers.

More and more it seems like it's either one way or the other, unfortunately.

On the other hand, the original owner of the company said it would be possible with the use of an additional switch, inputs and rewiring. What it would cost me and whether it's worth it, that's another question.

"Unity gain" refers to a type of home theater bypass that some two channel preamps have. It is different from the type of bypass that works even if the two channel preamp is powered off. The Cary SLP03 for example has this feature. There is some controversy over which type is superior. Cary claims that a unity gain bypass helps avoid hitting your amp (and speakers) with too much signal if you inadvertently left your prepro "on" with the volume high when turning off the two channel amp in bypass mode.

Connecting the two channel preamp's output to the inputs of the prepro defeats the purpose of using a separate (high quality) two channel preamp. The high quality two channel preamp must be connected directly to the power amp to realize it's superior analogue abilities. A two channel preamp with home theater bypass, whether unity gain type or not, can do this since the output of the prepro is connected to the bypass input of the two channel preamp, and the two channel preamp's output is connected to the power amp's input.

"On the other hand, the original owner of the company said it would be possible with the use of an additional switch, inputs and rewiring. What it would cost me and whether it's worth it, that's another question."

In other words, they can install a home theater bypass.

skiman,

thank you for the explanation. The technician didn't explain it nearly as well. My (high quality) two channel preamp does not have this feature.

No, they meant adding another pair of single ended, rca inputs to the back of the amp, with a switch. Whether this is possible, or not, without compromising or changing the entire wiring approach, I do not know, nor do I think does he.

It's looking like the best method will be to relocate the 990, so I can have access to its main switch and manually plug in and pull out the 2 channel preamps out/inputs.

Any thoughts?

thanks,

John

How about something like this?
http://www.kramerelectronics.com/indexes/item.asp?desc=69

Hullguy,

How would I use this unit? Could I attach only the balanced L & R XLR outputs from the 990, as well as the pair of single, rca ended, two channel preamp outputs to this unit and then output a new, pair of XLR cables to the L & R XLR inputs on my amplifier, switching between the two inputs via this unit? Is that how it would work out for my application? I'm not sure it actually allows for switching; either that or I'm missing something?

How much of a degradation in sound quality would I be facing?

Man, this sure seems confusing; or, am I just getting old?

thanks,

John

Why don't you use unbalanced cables for all connections and just use a simple passive switch box at the unbalanced inputs of the power amplifier for the music only channels? Honestly, using the balanced connection, considering it involves yet another active electronic stage, will have the potential to degrade the sound more than the simple unbalanced setup I described. This assumes all your gear has unbalanced connections in addition the the differential.