Ozatschek, there is a huge difference in the day to day operation in heat and expense between the 610s and the 210s and still a good sized difference between the 210s and the 110.
I assume you have thought about the amount of heat two Ref 610t amps put out and the cost of operation when they need retubing? I have Ref 210s and a Ref 110 and the 210s put out more that twice the heat of a 110 - there are more than twice the tubes. I my room is not small (17x27x10 feet) the 210s will raise the temp by 3 or 4 degrees and another 1 or 2 if I am listening at loud levels. Plus I retubed the 210s from ARC and it ran about $1,800 w/shipping. I don't know what it costs to retube the 610ts but I think it is at least $4.5K given the number of 6550 tubes needed. If I used only the 210s, I would need to retube every year and a half to two years.
As for differences in sound, I just placed the 210s back in service after using the 110 for 3-4 months and I like the 210s better on my Vandersteen 5As. For me its more about slightly different flavors than a clear winner but the 210s play louder and have more punch.
Do a search for davemitchell in the amp/pre forums. He has several great posts on ARC amps. He disclosed he was an ARC dealer and I found his comments on ARC VTM200s and Ref 210s amps that I have had to be on point. I am not in total agreement with the 210s vs 110, at least not with Vandy 5As but that could change with other speakers since the 110 is little more tubey sounding. I would email Dave if I were you.
FWIW, I recall running accross some desenting opinions on the previous Ref 600 series amps. Obviously there is more power for though loads. But I recall some wondering if there are issues getting that many output tubes to work togeather.
Good luck, Terry
