OK Robert, I'll be true to the question: just
one amp. That being said, I am taking into account that I will have
nothing else in my arsenal. So, it will have to fit the bill for each and every kind of playing I do, and venue I play at. It needs to be versatile for practice, playing live, and recording. Most of all, it needs to sound
killer!
Again, I need look no further than my own studio to find that one, indispensible, fantastic-sounding amp: the venerable
Fender Cyber Twin. The amp's not only a chameleon of sound, it's an amp that feels and reacts just like the amps it emulates. But that's only the tip of the iceberg. Sweet, vintage-style Blackface cosmetics; (2) 12" factory-installed Celestion G12T-100 speakers barking out 130W of tasty Fender tone (yeah,
factory-installed Celestions - yummy!); more than (30) models of some of Fender's most sought-after amplifiers, as well several other classics; and a host of top-quality effects. Combine that with the ability to mix & match drive (tube) sections, MIDI recording capabilities, a bevy of output options, and there is very little that this amp can't do, and sound good doing.
Boy, I'm a lot of fun, aren't I? Kinda' like taking a date out to eat at McDonald's, and having her actually be happy about it.

Ha ha ha!
And so, I give you the Nelskie Dream Combo: 1990 Epiphone Les Paul + Fender Cyber Twin = Electrified Nirvana.