Changed amps - center image moved

Wow Al....many thanks for your interest and help!! One interesting tidbit...when I had the Samsons, I used a Cardas XLR to RCA adapter at the DAC side (so to get more output via the AES outputs on the DAC & not need a preamp), thus could use RCA IC’s. The imaging was superb.

You’re welcome, Jeff. But I’m wondering about a couple of things in regard to this statement, if I am correct in interpreting that you were using XLR-to-RCA adapters on the analog outputs of the Theta DAC/Preamp:

1)Using XLR-to-RCA adapters on the XLR analog outputs of the Theta would not have given you any increase in output, compared to using the RCA outputs. As I mentioned earlier the RCA output connector is wired directly to one of the signal pins on the XLR connector, and it is that signal which would have been provided to the Samson via the adapter. The other signal on the XLR connector would not have been used. The reason the XLR output is specified as having twice the voltage of the RCA output is that the spec for the XLR output reflects the use of both signals.

2)More importantly, most XLR-to-RCA adapters short the unused signal (usually pin 3) to ground (pin 1). My understanding is that Cardas adapters can be special ordered to leave pin 3 unconnected. While shorting pin 3 to pin 1 is proper practice for adapters that are used on inputs, with most designs it is definitely something that should be avoided on outputs. Do you know if the Cardas adapter you used shorts pin 3 to pin 1? If you are uncertain that can be easily determined with a multimeter, if you have one.

If that adapter shorts pin 3 to ground (pin 1), given the extremely low output impedance of the Theta (25 ohms balanced, corresponding to about 12 ohms for each of the two signals in the balanced signal pair), a concern would be that over time the short might have adversely affected the health and the performance of the Theta’s analog output circuit which drives pin 3. And if so, that could conceivably account for the imaging issue, since the pin 3 output is now being used (while not having been used when you were connecting to the Samsons).

In any event, good luck as you proceed. Regards,
-- Al

Guys it is possible one speaker has been hook up with the leads reversed. This will in fact cause such a sonic character. This is a reasonable course of action. Kind of simple...right? If not the cause, then yes the amp sounds different with the speakers. Small speaker placement changes may also help if not a polarity issue. 

Guys it is possible one speaker has been hook up with the leads reversed. This will in fact cause such a sonic character.

Bill, yes it will, but as I and Seikosha indicated it will also cause big-time sonic degradation, which the OP has indicated multiple times is not occurring. Although as you indicated it’s easy enough to check, and it is certainly something that should be checked.

If not the cause, then yes the amp sounds different with the speakers.

Not necessarily. The Theta DAC/Preamp is also suspect, as I explained in my previous posts. He is now using a signal path of the Theta that was not used with the previous amp. And furthermore he is now using an output circuit of that previously unused signal path that may have been shorted to ground over a prolonged period of time, and whose condition is therefore highly questionable.

Best regards,
-- Al

Yes that also Al. The point is these are all valid points and will in the end sort out the end facts. A system can still sound "good" subjectively out of phase on one or both speakers. I have experienced it. 

It is also possible that the amp itself could have one channel wired out of phase with the other. With balanced equipment this is very easy to do by mistake!

I would reverse the speaker connections on one channel only just to see what happens. Does the center image improve? Is there less information sitting in the speakers and more spread out between them? If so, then we will know that there is indeed a phase problem, and the next step will be to find out where it is.