Sound — 9
Like I said above this is not a plug and play amp, and for those of you who aren't patient and don't want to spend time with an amp then I wouldn't get this, but once you get this amp dialed in... Oh my god. The clean channel is as good as anything I've ever heard, even Fenders. It's so good that I don't even use effects anymore save for the reverb on the amp. Channel 2 is not something I use much but unlike most 3 channel amps the 2nd channel here actually sounds good! When I use it its usually for a classic rock type sound so I use a lot of gain on it. The Mark I voicing can get you that classic Santana lead tone if you dial it in right. Channel 3 is where I spend most of my time. I'm primarily a metal player and this amp can and does everything you could possibly want in the metal genre, from Metallica and Dream Theater to death metal and to even fusion. Its very possible to find your own sound on this amp as well, don't let youtube demos fool you. The voicings on this channel all make a huge difference in the tone. The famous IIC+ voicing is actually my least favorite because while it gets some smooth lead sounds, it sacrifices some heaviness and definition in the lower registers. The Mark IV setting is where its at, as it gets an amazing rhythm sound while delivering a searing lead tone as well. You know its heavy when you can literally feel the ground vibrate when you hit an open E. I don't use the Extreme setting much because its well, too extreme. I don't need that much low end, but if you're playing death metal or anything where you want some major chunk, you'll be more than content with extreme mode. Also like a previous reviewer mentioned, the bass knob makes or breaks this amp. Any higher than about 4 and your amp will lose all definition. The different wattage settings are a godsend because this amp is LOUD as shit on 90w and sounds like total ass unless you turn it up. If you bring it down to 10w you get all the saturation at much lower volumes (even though its still loud as hell on this setting). I never use the 45w setting, but basically the amp sounds good on all wattages, and that goes for all the channels. The clean channel doesn't break up, and the distortion just gets meaner the louder you go. To get an idea for how loud this amp is, I'm running it through a Mesa 2x12 Rectifier cab and I've never turned it up higher than about 5, and that's with the channel masters turned down fairly low as well. Its also fairly quiet for it what it is, it hums a little but there's no annoying uncontrollable feedback like you would get with something digital, totally organic all the way, and the mute button on the footswitch gets rid of all of it if the hum bothers you. Another thing, it cuts through everything in a live situation (even the drums) so if you're worried about getting lost in the mix, then you won't have any problems there. All in all a fantastic sounding amp.
Overall Impression — 9
I'm really starting to love this amp. Its made me a better player because it doesn't hide your mistakes. I upgraded from a rack setup that was very haphazard compared to this and I love how much easier it is to gig now. I play lead guitar in a progressive thrash band so this really covers the whole spectrum of what we do, from pristine cleans to crushing rhythms to soaring leads. Its a wonderful amp and I would recommend it to anyone that has the patience to dial it in, because its not going to sound amazing out of the box, but once you get it dialed right, its totally worth it. I would give it a 9.5 if I could but not a 10 because it still doesn't beat some of the higher end Engls or other amps of that nature that I've heard, but unless you have 4 grand to drop on an amp then you should get tone of these instead.
Reliability & Durability — 10
I haven't had this amp long enough to really know how reliable it is, but its built like a tank and its a Mesa so I'm assuming its pretty damn reliable. Mesa is also a wonderful company that provides a warranty on the amp and even on the tubes! I also got cases for the head and the cab when I bought it, so that was nice.
Features — 10
Well after years and years of wanting to own a Mesa, I finally bit the bullet and purchased a Mark V, and I wanted to wait a few weeks to review it as it is not a plug and play amp by any means and I wanted to spend as much time tweaking it and gigging with it as possible to get the full idea of its range. I don't think I need to go into full detail about how many features this thing has if you know anything about this amp or the Mark series in general, however I will say this is probably the most versatile high gain amplifier on the market right now save for an Engl SE or if you're into digital stuff an Axe Fx. There are so many different possibilities with all of the channels having 3 or more voicings, the ability to Switch between pentode and triode, 10 45 and 90w settings, reverb, EQ, etc. Its a bit overwhelming but unlike the Mark IV this amp is much more user friendly to someone who has never owned a Mesa before. It also comes with a footswitch that allows you to Switch between the channels and options to Switch on/off the reverb, FX loop, and EQ. It also has a solo boost and a mute button which are really useful for live scenarios.