Soundstage vs background noise?

Tube amps, IME, rarely take a back seat to transistor amps when it comes to soundstage. So I am suspicious that there is something else going on- perhaps related to the noise you are talking about. You might want to test the smaller tubes in the amplifiers- if they are getting weak you could well experience something like this.

A tube power amp might have slightly more noise than a transistor amp, but it should not really be noticeable, since a typical noise figure for any tube amp made in the last 40 years is -95db or better. That's pretty hard to hear on most speakers. So I am thinking there is a good chance your tubes are shot.

I appreciate all the comments. Ralph, my experience is that tubes are just noisier than solid state. Admittedly I do not listen to music with my ear 4 inches from the tweeter, but I have to tell you, at that close range I always heard a hiss through the speakers and now with SS (I'll give a plug- Pass Labs) it's dead silent. I have to think that has to make a difference.

Some transistors are indeed quieter than some tubes, but not all. IOW you are for the most part correct. Unless you have high efficiency speakers though, it sounds to me like you have a very minor noise problem if what you describe is the extent of it. If you listen further than 4" from the speaker, its likely not a problem :)

However, just as a point of reference, our speakers at our shop are 93 db and we have to put our ears right on the driver to hear the noise floor. My speakers at home are 97-98 db, and I hear some residual noise about 8" from the mouth of the horn. I have found that transistors tend to make a similar amount of noise on that system.

IOW with most speakers you shouldn't be hearing anything. That is why I suggested noisy tubes, as that is a common issue with weak tubes.

Its really in high gain circuits, like a LOMC phono section, where noise really becomes a concern.