Tube amps under $7500

Points well made and I'm not familiar with Legacy speakers.  However,  I pair a VSi75 with my Dynaudio Heritage Specials and it seems to drive them just fine.  And when playing vinyl have a Ref2 SE phono pre use a LOMC Lyra Delos and again seems to sound fine.  Of course I have a smaller room and moderate volume levels.

Audio Research i/50 meets your requirement for tube with balanced inputs and at the price point you mention.

@chenry Unfortunately, this unit is an integrated whose preamp section is not versatile enough for my needs. Also, its tubes won't deliver the current needed to handle the low impedances thrown up by my Legacy speakers. Seems the only tube amps likely to do this are the big ARC separates and the BATs with their monster output tubes. So I will be looking for a deal on one of those while pondering whether to just cave and go SS after all. Some are reputed to sound rather tube-y, or at least will operate in Class A to 40-50W.

Balanced is not differentially balanced. I am pretty certain that BAT is differentially balanced and I am not sure about ARC. My guess is not. Only makes a difference if your preamp is differentially balanced. True you can beat some speakers into submission with higher power, but you will not be getting the most from these tubes amps. It is not just impedance but also swings.  

I have a room with separate and a simple room that I have tried some integrated amps. Right now I prefer the simple room.
 

I stumbled on the Audio Hungary a50i and really love this amp and see no need to move on. It plays any type of music I throw at it. Can’t say that for the Conrad Johnson cav 45s2 even though that is a wonderful amp for certain types of music. I tried the ARC and BAT and others but just wasn’t for me.
 

There is a 75 watt Audio Hungary balanced a75i on US Audiomart for $3800 retail $9000. There is something very special about class A with tubes.