Please see my review of the LS16 mk. 2 vs. the LS25 mk. 2 at www.10audio.com. Even though the LS16 I reviewed is the later model, the review may help with your question.
I own an LS25mkII, and it's not as "tubey" sounding as some other tube-based preamps. IMO this is a good thing, as I find many tube designs to be overly warm and syrupy-sounding.
I feel it's a good compromise between the warmth of a "tubey" tube preamp and the detail of a SS preamp.
Oh, and another thing - it seems that any and every ARC thread draws ARC bashers out of the woodwork. Reb, Sutts - nice to see you guys don't disappoint! :-) Apparently the ARC bashers wait anxiously to pounce the moment they see anyone mention ARC.
Whatever floats your boat! ;-)
I had been using an SP-9 MK II for about ten years. A few months back I tried an LS-16 MK II. It was an improvement but not a very big one. Can't really say if it was the preamp or some other variable (room?) that kept me from hearing the massive improvement the dealer said I would hear but I wasn't impressed for $3500. About three weeks ago I spotted a great deal on a LS-25 MK II and went for it only because I knew I couldn't lose (unlike buying a new LS-16 MK II). Well the sound was kind of disappointing in the sense it really didn't sound any better than the LS-16. It does sound good but there may be something to what all these folks keep harping on about the LS-16/25 MK I and the LS-5 series. I was really looking for an LS-25 MK I but I've only seen one in the past six months, I think I understand why now! At this point I'd like to hear one in my system before making a judgement, but that won't happen unless the local Audio Research takes one in on trade. I can't spend that kind of money again for a while. My wife was understanding the first time ....
I went from an LS-25mk1 to the mk2. Then back to a 25mk1. Had a sickening experience with their digital 150.2 amp and cd3 mk2. Swore off ARC for life now. Went as far as to sell the 25 mk1 even though I liked it. Now own the PSE HL-1 hybrid. All tube voltage gain/mosfet current gain-output.
I speak from first hand experience. There is no music in the 25mk2 with the 6H30 tube. YMMV.
Changed nothing in my system when I went from mk1 to mk2. This April marks 3 yrs since that horrible mistake. All different components now. Basically that screwed me up big time. But now I finally have recovered and have music again. I could see the 25 mk2 working well with the typical dead, flat sounding solid state ARC component. And wouldn't be surprised if they made some revisions.
I can understand that there are some individuals out there that just do not like ARC for some reason or another, and I respect their opinions, (that is why I started the post after all), however if the 6h30 tube is inadequate as I am detecting from some of the posts above, then why are some of the major hi end companies such as BAT, ARC and Conrad using them? I would think their integrity would be on the line if they all of a sudden went to a tube that was worse than the 6922.... Doesn't make sense on an "audiophile" standpoint, or a "business" standpoint either..........
I am curious if I took the "ARC" out of the equation, and just asked for a comparison between the 6922 and the 6h30 tube if I would get different opinions.
The REF One does have trimmers. The LS don't need to be biased, only "balanced" tubes are required : triode1 = triode2 for each tube.
You only need to change the ones of the first and/or second stage(s) to tune the sound.
Try the Amperex 6DJ8, still cheap ;-), but sounds good. The current Ei 6DJ8 is not bad also.
ARC units are "very sensitive" to tube rolling, you'll be able to tune the sound with your MkI, KEEP it !!! don't upgrade.
Check on Tube Asylum for more feedbacks and contact ARC for more infos, their staff is very helpful.
I talked several times with Leonard, he's cool.