Here's a copy/paste from a post I put up in another thread here last month. Check out the thread, there's some good info about the Mark V 25 and other lunchbox amps.
viewtopic.php?f=3&t=184624
I finally got a chance to play the Mark V: 25 a couple days ago, and I really dug it. I'm a Mark series fan, though. Ran it through a new Mesa 1x12, which also sounded pretty nice. I noticed a pretty big volume jump between the modes on channel 2, which I didn't like. I dialed it in on IIC+ mode, then switched modes. The volume jumped up a bit on Mark IV mode and even more on Extreme.
I had to get it opened up a bit to find a high gain sound I liked. At 8' o clock on the master, it was really thin (assume no volume=7'o clock). No amount of EQing seemed to get rid of it. Bringing the master up to around 8:30/9:00 ish fixed that problem instantly. The bottom end filled out, and the feel of a Mark series lead channel suddenly appeared. I was still at "quiet" volume levels, but starting to push it. Not TV or conversation volume by any means. Couldn't hear a word from my girlfriend or the guy working there, both standing right next to me. The master is really touchy, as per most every Mesa amp. This amp could do with a Global Master, IMO.
I had the EQ knobs pretty much all set to 9 o' clock or slightly under. I didn't find any use in going over that on the controls. On the graphic, I started at the classic V shape with the 750 slider a couple notches above the bottom. Wasn't feeling it there, didn't have the punch or clarity I was looking for. I took the 750 slider all the way down and found it. I tried playing around with 750 a bit more, but in the end leaving it all the way down was the best at the time. Pushed the 6600 down just a hair to deal with some fizz, and found a very useable tone. This was in Mark IV mode, which I preferred. It had more balls to it, I guess. I liked the low end in Mark IV mode. Didn't play with Extreme much, was having too much fun with IIC+/IV. I had very little trouble dialing in a good high gain sound, but as I said I'm a Mark series guy. If you don't have experience dialing one of these in, it can be a bit frustrating.
The Crunch mode on Channel 1 is pretty cool! I got some nice rock sounds out of it really quickly. You can crank the gain up and get some very pleasing high gain sounds too. Turning on the EQ brings a lot of versatility out of Channel 1.
Switching Channel 2 down to 10 watts cuts a bit of volume, but again the tone thinned out. I did manage to dial it back in, but it wasn't perfect. Channel 1 Crunch Mode at 10 watts was cool, though. I liked that setting for just over the edge of breakup sounds.
I was playing a '58 VOS Les Paul, a '59 VOS, a brand new Private Stock PRS owned by the guy working there, a 2006 Gibson Explorer, and this crazy Gibson V. 2008 Guitar of the Month model. "50 Year Commemorative Flying V". Second entry down on this page.
http://gearpipe.com/featured-post-gibso ... -detailed/
Overall, I was really impressed. I would love to have one at home. I think I'd like the Mark V: 35 even more, but sadly they didn't have one in stock at the time. If the 35 can get those sounds at the same volume level plus the extra versatility, then I am on board.