VTL ST-85 vs. VTL ST-150 or rather EL34 vs 6550


I am curious to know the sonic differences between these two amps. Aside from the obvious that one is higher power than the other, how much different are they in terms of sonic character from one another? I ask since the 85 uses the EL34 (which seems to have a following in Tube circles) and the 150 uses the 6550, also well-respected but different. At the present time, I am using an 85 until my brand new 150 arrives tomorrow. I really like the overall nature of the 85 quite a bit, and my line of thinking in ordering a 150 was that it would provide the same sound, but with just a little more crunch. Now I am finding out that may not be the case since the output stage tubes are completely different, 85 having EL34 and 150 having 6550.

So my question is; are these two amps in any way different as far as how they present the music (not the power they have)? Or should I expect the overall house sound of VTL (which I obviously like)to show through on either amp? I don't want a harsh sound, and the EL34 seems to be quite the opposite, very nice, slow, romantic, smooth etc. Just not sure about the 6550 since I have no experience with it, and this has me worried that I won't like it on my 805s speakers, like I like the 85/EL34.

Thanks for any help anyone can provide, much appreciated.
jc51373
Cyto..Yes I have, am now actually..Not really with much volume though since I am using it when my wife goes to bed.

Bea at VTL said for break in Terode was best since it runs at full power. So for the most part it has been tetrode.

I notice a difference in the two for sure. And triode is definately cool for low level listening.
Couldn't help but chime in here gents.
I just took a leap of faith and went from the ST 150 (going to hang onto for a while) to a new pair of the MB 185 signatures. Both use 6550's, with the 150 having the SED winged, and the 185's having oem's.
Out of the wrapper the 185's present a larger soundstage, to the point of having to reposition my speaks. They sound considerably "leaner" which may be due to tubes not settled in quite yet.
I began with Antique Sound Labs AV-20's, and it was instant tube mania, but they would run out of steam with some volume applied, so it was onto the ST 150.
The ST 150 is a gem, its reliable, sexy, and a brute at only 150-side.
I also noticed a gain change between the 150-185's as the pre's volume doesn't get to far from home before the room is full of sound. Both are very quiet amps, with the 185's having a tad more background hum, but not noticable from the listening area.
I use a lowley VTL LS 2.5 (with Steve Huntley magic) to drive them, and am considering trying a 5.5 to try the balanced i/o.
I hear ya Jc, piano along with acoustic guitar are so life like it isn't funny. I have listened to Clapton unplugged swapping between my favorite ss amp and the 150, and the difference is not subtle. Fingers sliding on strings, or the hammers strike of a piano key are soooooo life like you'd swear, well, you know........
Cheesehead, what is the favorite ss amp you refer to?

JC51373 who did you order your amp from? I've been interested in the VTL's for some time, but don't have a dealer that's close. Did you get an in-home trial period?

Thanks