I got a chance to try out all these amps this past weekend. Store demos only, not on a gig, but I feel like I got to hear their character and their individual capabilities. I was able to demo the Acoustic Image at New York Bass Works while I was there getting some repairs done. It was a Focus 2R head (a slightly older version with 600 watts vs. the new ones with 800 watts) along with the Ten2 Extension cab. Check out my mini review here. I tried the other amps out at Guitar Center using my NYBW 6-string into a Markbass 1x15" cab. My comparison categories are a bit odd, but when I test things out I look for specific traits. Hopefully my observations are helpful to someone else as well. Full disclosure - my regular rig is a Demeter Preamp, Crown Marcrotech Power amp rack setup. So my reference tone is a warm, open sound with a ton of headroom available. My main goal with these comparisons was to get an idea of how some of these micro heads may match up. Best "plug in and play" tone: With all EQ set totally flat it is a toss-up between the Ampeg or Acoustic Image. I didn't hear these two side by side, but hours apart on the same day through different cabinets, so my comparison is very subjective. If pressed, I'd probably give the edge to the Ampeg. Both of the Markbass heads seemed a little dark, like the highs were tempered a bit (the VLE and VPF were off at this point). They didn't sound bad, just not as open as the other two. Best "fiddle a little and get a lot" tone: The Markbass heads take this one. Turn that VLE knob about 2/3 the way up and you've got instant vintage. Very cool. Turn it back down and spin the VPF and you've got a very nice scooped tone which works for slap and a smooth, crisp fingerstyle. Both those controls work very well...much, much better than I was expecting. Well done, Markbass. Most useful EQ, or the "fiddle a lot and get a lot" award: goes to the Ampeg. The Markbass EQs worked fine, but the Ampeg had the most versatility with the Ultra High and Low buttons, and the 5-way selector for the mids. A lot of sound manipulation at your disposal. The Ampeg also has a built in compressor, although I'm not likely to use it. The AI EQ is very basic (and the EQ centers seem inferior to the other heads), although the variable high pass is very useful. Most "volume per pound" award: They all seem capable of pretty high volumes. The Markbass amps probably take this one because of their super light weight. The AI is right up there as well and really kicked with the Ten2 extension cab. The Ampeg has more power, but is the heaviest at a whopping 15lbs. Most headroom: This was an eye opener, but the result was not totally surprising. One of my bigger concerns with these lighter amps is their ability to handle transient peaks: slap on the B string, digging in fingerstyle, etc. To test this out I did my best to set the perceived volume at the same level for all three amps. The Ampeg was the top performer here, followed closely by the AI, with the LMIII a little ways back from there. The F1 did not do well as it seemed to "chop off" the percussion attack of this playing style. The explanation for the differences I noted here is not necessarily amplifier brand, type or class, but that the Ampeg and AI put out more power than the other two (600watts for 300watts during these tests), and the additional headroom allows those peaks to be properly produced. Although, the LMIII clearly outperformed the F1 in this regard and that may have to due with amp class. Hmmmm. Either way, I don't doubt that some of the bigger Markbass heads would do better in this department. And for some players this transient capability is not crucial and the difference is irrelevant. I went into this comparison with the mindset of if I found anything that blew me away I was going to purchase it. Well, that didn't happen, but I was very, very impressed by all these amps. They all did several things well and I probably could use any of them on a gig and not have too many complaints. If I were forced to purchase one of these tomorrow, if I were picking by "best tone, most power" for the price I'd go with the Ampeg ($800). If price were no object and I wanted to be sure about reliability I'd go with the AI (~$1100). If price was the biggest concern I'd go with the LMIII ($600). The more expensive F1 ($800) did not perform as well as the LMIII, I'd probably leave it off my list because of that.