I recently purchased one which came with reference level modification from the Great Northern Sounds (GNSC). It also came with a quad of Siemens Falcon 6922s recommanded by Steve Huntley of GNSC. (The previous owner went all out with the mods) The LS-25 replaced the LS-2B Mk II that had been in my system for almost 8 years. In short, I was very impressed with the overall improvement. (I did not know my Thiel 3.6 was capable to produce that kind of bass and soundstage, and I had them for 10 years) The other day, we did a shootout between my modded LS-25 and a Sonic Frontier Line 3 SE. Everyone preferred the Line 3 slightly over the modded LS-25. But when I took out the Siemens and inserted a quad of Amperex white label USN-CEP 7308s, it was like we were listening to a different linestage! All 4 votes went to the LS-25 with Amperex tubes. The Amperex simply embarrased the Siemens! (I had tested those tubes on my TV7D/U tube tester when I first received the unit, so I know they are still OK)
Regarding the GNSC mod, I have been wanting to do a shootout with a stock LS-25 MkI to see how good the GNSC mods are. I sent out an invitation on Audio Asylum but got no response. I guess there aren't too many of them out here in the San Francisco Bay Area...
My next challange will be against a Ref 2 Mk I and a Ref 2 Mk II.
As for modifying ARC products from 110V to 240V, I have heard that it is a closely guarded secret and that ARC does not like to do that. Do a search on here and AA, I think there was a thread a few weeks ago discussing about that.
FrankC