Little 'grab and go' amps (like my Swart AST Pro) are great tone machines in the right space -- i.e., following the old rule "little room, little amp; big room, big amp." But in the wrong room little amps can sound, well, really small. The reason is that these little guys are, more or less, all mid-range (the bottom end is not wide and deep because their cabs are tiny and the tone stack is mid-shifted for cutting leads and a smokey top end.
What about that elusive little amp that sounds like a big amp?
Well, don't worry, they exist and I'll give you three great examples right here that are still portable but sound larger than you might expect. What they have in common is (a) larger cabs, often 20-22 inches wide and (b) a 'scooped' midrange, i.e., big bottom end and brilliant top with less emphasis on the mids:
3. The classic little big amp that all others are compared to is the blackface Fender Deluxe -- if you could only have one amp, the Deluxe should be the front runner for your consideration.
2. The Vox AC15 (w/ Blue 1X12 Celestion) -- maybe my favorite amp of all time. The bottom end is big and nothing beats the top end chime of an AC. Pair this bad bad boy with a Tele and you're in sonic Nirvana.
1. The Mesa Boogie Express (and now the Plus 50) -- maybe the best clean sound in a 1X12 format of all time. The updated Express Plus features the clean channel from the Lonestar. This might be the best American-made, tube amp bargain on the market today.
What's your favorite little big amp?