Changed amps - center image moved

I've had several instances after I've made significant upgrades that I've had to re-position my speakers to allow for a change in soundstage height or width.

I find a diffuse center image is often 'fixed' by using cones beneath the amp. One amplifier I reviewed came with Audioquest Bigfeet (sorbothane) and I felt the imaging was quite non specific.The designer told me that was his intention as it is more like a real concert experience he said. Well I record with single point mics and the imaging is very specific when the system permits. I consider myself an image freak basically as I have experienced a lot of live music over the years and to me this heightens the reality of reproduction considerably.
 Now another more expensive model amp of the same brand came with Stillpoint feet which I liked more and they imaged fantastically but were also monoblocks. When I put a set of polycrystal cones beneath the less expensive amp I found the image far more focused which is the effect I hear when using cones under my gear. I like to use squishy feets under transports as these create vibrations but I use Black Diamond Racing cones and Brightstar brass cones too. I find I can tune the bass dampening with these but then I also experiment with the material they are placed on and  I have used glass, rubber, concrete, and hardwood beneath my components as my ears inform me. Some of the better stands offer shelves of different materials so I am not alone.
 Sometimes it is the chassis itself and mass loading works wonders. I like to use aquarium stones which come in an nice bag. Sand is just too deadening. The $2500 amp had a rather flimsy top as opposed to the 5X more expensive model that was hewn from a solid billet, which is why you see this done on many high end electronics. On occasion I directly damped the circuit board with small pebbles (remember the diamond dust filled YBA gear or Shun Mook dots?).
 Balanced inputs usually also have additional buffer stages or transformers than do the single ended ones that I find degrade the sound. Check out schematics if you can I am not making it up. They just create the phase flopped output leg in most cases and buffering. However true symmetrically balanced circuits which are very rare do indeed perform better with a balanced input but then the preamplifier must also be true balanced. On my Tascam DV-RA1000 optical disk recorder the balanced input runs thru more than 3 additional opamps then does the unbalanced inputs for instance. Same with my Nakamichi MR-1 ins and outs. Balanced lines are designed for long runs that require common mode noise rejection. Not ever needed in any of my audio systems but you bet my microphones are all balanced lines. YMMV

Returned from Mexican vacation and the adapter arrived.  First I simply reversed polarity on one speaker...improved center image (using the XLR cables).  Then, switched to RCA IC's with the adapters (at amp only).  This fixed the problem!!  Perfect center image and huge depth in soundstage.  RCA out of Theta (no adapter) to Maker amp with RCA to XLR adapter......sounds fabulous!  The Maker amp is great.

Outstanding!

So it sounds like there were two problems that were simultaneously present. One of them being reversed polarity on one of the speakers, and the other being suggestive of a defect in one of the two signal paths to one or both of the balanced outputs of the Theta, as I had speculated. That signal path not having been used when you were connecting to the previous amp, and the problem perhaps having been caused or contributed to by the XLR-to-RCA adapters you were using at the Theta’s XLR outputs when you were connecting to the previous amp.

In any event, congratulations on the new amp and enjoy! Regards,
-- Al

The next step is to get rid of the adapters, perhaps having the XLRs installed on the ends of your existing cables.

I find that adapters often eat some of your dynamic impact, and its an easy thing to fix.