Changed amps - center image moved

Why is there so much concern about a center image changing with an amp change as though something has to be wrong with the rig? What jeffga has described is typical; every component has its own set of sonic characteristics. The description of more sound coming from the speakers is not out of character for switching amps; some have more of this than others. He didn't say there was a gross diminishment in the sound or that the center image had grown fuzzy, merely that it was more diffuse and larger. That is certainly not a concern as though something is wrong with the setup. 

Having worked with dozens of amps I assure you that such changes are common and to be expected. This is a very regular occurrence for me, and it is not the result of mis-wiring or another problem in the rig. The proper attitude should be to suspect something wrong if one swapped amps and perceptually nothing changed! The interconnects also influence the spatial characteristics of the sound, and moving from RCA to XLR can do so, as well as different brands/models. When you change both amp and cables you had better hear a significantly different sound, or else you have wasted your money/time (Unless the new component/cables are significantly cheaper and result in similar sound quality - but this is rare). 

jeffga, you said, "In a perfect world, I would have the specific center image plus the ultra wide space." I smiled when I saw that. This is the world of the audiophile; when you hear one setup with characteristics you enjoy, then change the rig, you have a shift in system characteristics, some more pleasurable, and some less. Welcome to crafting an audio system! It's an art that sometimes takes a while until you get everything just so. I suggest you revisit positioning, i.e. toe in, of speakers to get a ready solution to the center image, which may get you to the happy compromise sound between size and precision of center image. :) 

What you are experiencing is the amp change . Have had quite a few amps and the way they imaged was different for each one . You should not expect them to be the same ? 

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