I have a Nomad 100 head. I like it, as do several other Nomad owners like theirs. However, in my time spent on the
Mesa/Boogie Forums, I got the impression that the Nomad is the black sheep of the Mesa family. The control layout is very nice and easy to follow, IMO, but several people didn't care for the tones they got out of them; not enough gain, not enough heaviness, too loose fizzy, way too much mids, etc, etc, whatever their complaints may be. Judging by the language of the manual, and press material on the amp, the Nomad was intended to be a less expensive jack of all trades when it came to tone, and thus is considered by some to be a master of none in that regard. However, since there are some satisfied owners of the Nomad, either the amp can't be
that bad, or there are some people weird people out there. I'll vote for the former, though I likely fall squarely in the latter category.
There's three differently voiced channels, ranging from clean, medium to high gain, or anywhere between depending on how you set the knobs and switches. The 1st channel has a warm clean that is very nice. Not as awesome as a classic Fender clean, but still very, very usable. In it's alternate mode the 1st channel can also double as a light to medium gain channel that can be set on the edge of breakup or all the way into an overdriven crunch.
The 2nd channel has been described to me as a "Classic Boogie lead", which I take to mean it's supposed to be voiced similar to the lead channel of an early Mark series or something. Having not played any early Boogies, I don't know how true that is. What I do know is that the 2nd channel is very fat, with big round bass, and a very smooth voice. The gain can be set very low just on the edge of breakup, or all the way up to medium high levels for a nice, thick sweet sound. IMO, this channel does well for lead work with it's smooth voice. In it's alternate mode the gain is bumped increased, and can be taken to very high levels, where you can get a compressed, sustaining lead sound, or an awesome heavy thick crunch. The crunch of the second channel is what sold me on the amp.
The 3rd channel was described as "a traitor to the Crown." in press literature, which makes me think this channel is supposed to be voiced similar to a modified or hot-rodded Marshall. I don't know how true that is, IMO, a Marshall makes for a better Marshall sound than a Nomad does, but that doesn't mean the 3rd channel is unusable. Of all the channels in their normal modes, this one has the most gain, so it's best to be cautious with the gain knob. The bass is also set in slightly higher frequencies than channel 2, which makes channel 3 sound tighter and faster. If your chops aren't totally up to snuff, or your EQ is dialed weird from one channel to the other, the 2nd channel can sound slow and clumsy in comparison to Channel 3, or Channel 3 can sound unduly thin in comparison to Channel 2. Channel 3 can go anywhere from a medium low gain light crunch to a very high gain, suitable for tight and fast hard rock or heavy metal rhythms or bright, shreddy leads. In it's second mode, the gain in Channel 3 gets pulled back and it can be set lower, from not-as-heavy crunches, to a clean, on the edge of breakup sound, for blues.
The reverb is nice on the 1st channel, but on the 2nd and 3rd channels, it is subtle at best, and weak to non-existent at worst. There is a mod out there to change a couple resistors to bring the reverb levels for the latter channels up to one comparable to the first channel, but stock, it isn't that great. The effects loop is the parallel loop with a mix pot, but even with the mix set to 100%, you may have a hard time using digital effects in the loop. Again, there is a mod out on the Internets to address this.
A tip for trying to get nice sounds of a Nomad if you decide to demo one to see if it is the amp for you: for the heavier, higher gain sounds, pull the gain knob back, and throw an OD type boost set on the edge of breakup in front of the amp. Upping the gain on a Nomad not only adds more compression, but also lower mids as well. Too much of both and you get mud. The gain pulled back with an OD boost in front will sound tighter and more articulate. Secondly, you'll probably get the best sounds with the EQ knobs near noon, even the mids (especially the mids).