In my opinion, Sim and Aragon are a little on the "dark" side in the midrange, but have great bass control. The Marsh tends to be on the "brighter" side in mids, and is nicely neutral in bass. All 3 can be a bit bright in the treble, depending on speaker/cable. All have good detail and soundstage. A critical factor to consider here is that these 3 amps (like many amps) need a LONG break-in period before they can be fairly evaluated. They are all quite harsh when new; so try to borrow well-broken-in demo units from a dealer to hear in your home system. It sounds like you have a flexible price range ($2K-$5K for the amps listed), so you should look into others as well. Let us know of any comparisons you make....
