Seeking more 3d imaging, deeper/wider soundstage

Realremo - Atmasphere's comment related to the speakers themselves being out of phase not the musical signal itself. Make sure the + and - from the power amp goes to the + and - to the speakers. If one is incorrect, then the images will be outside of the speakers rather then in between them.

Concerning the signal itself being inverted, you could resolve this by inverting the speaker cables at both speakers .but I don't think you will notice much here. I had a DAC with an invert switch and I could flip it again and again and no way would I ever pass a blind test that anything was changing.

Concerning repair of vintage electronics, there are such repair places all over the country. And people here would be able to point you in the right place with a simple query. Some of the companies in my list, CJ, BAT are still in business.

Tubegroover - You will notice that I had no ARC products in my list. And this is because, for me anyway, the ARC magic starts with the SP-8, and this typically sells in the $1500-1900 range which is outside of the budget here.

A suggestion that won't cost a dime: Move your speakers further apart and/or bring them out into the room some more. Also, experiment with more drastic toe in once you've spread them apart. You may be surprised.....

Realremo, to check to see if your speakers are in phase, you simply reverse the connections on the back of **one speaker only** - not both.

If this works, you will immediately notice greater center fill and sharp images between the speakers. If it does not work, the images will become more diffuse.

Regarding tube equipment reliability: tube amps and preamps are usually fairly reliable- some more so than transistor equipment- it depends a lot on the manufacturer. The issue is the tubes themselves, which are considered user-replaceable, which is why they are in sockets. When a tube goes bad, quite often it will tell you about itself :) So you don't have to send the product somewhere to get serviced, you simply replace the tube and you are down the road. If it were any other way it would not be possible for tube equipment manufacturers to be in business for decades at a time!

Its important to distinguish between the reliability of the chassis as opposed to that of the tubes. For example in our amplifiers if a tube fails it will not damage the amplifier (although it could blow a fuse); our amps are stable enough that I have a demonstration I do at audio shows where I remove power tubes from the amp while it is playing music. You don't hear any change- the amp continues to play as if nothing happened. Now not all tube amps are like that but OTOH its not really important- they will hold up just fine, hence the existence of used tube amps that are heavily sought after 50 years after they were made!!

IOW don't worry about the reliability. Right now it seems you have bigger fish to fry. Keep us informed of your progress.

Realremo, no worrries, mate, there's a very good chance the next CD you play is also inverted phase, so it all evens out. Always look on the bright side.

So interesting things happened last night. I found the right
speaker was out of position a few inches, so I fiddled with
it using a tape measure. Now I have both of them about 28
inches from the back and side walls. There is about 6 feet
between them and I sit 8 feet from either speaker. Imaging
returned, soundstage grew in width and height, but still
hovers around the speakers.
I listened for about 2 hours, enjoying the improvement my
tweaks gave, then I tried inverting the phase on the left
speaker. The soundstage wrapped around my left shoulder and
behind me. I was pretty stunned at the difference this made.
Later I listened with only the right speaker out of phase,
the center of the image traveled out from between the
speakers and sat just right of center in the room.
I used to have my system on the long wall of the room, I
swapped it to the short wall earlier this year, to get a
little more distance between the listening position and the
speakers. The imaging and soundstage I had on the long wall
was lost. I have been chasing that sound ever since, I think
now I know that one speaker was hooked up out of phase on
the long wall, accidentally. This actually sounds really
nice for certain electronic music, but it makes tracks with
vocals sound a little strange. Haven't tried classical with
this yet.
So, no one hooks up one speaker out of phase on purpose, do
they? This is an incorrect hook-up, right?