I realised after about 2 years of playing that "ok, been doing this for a while, I really should invest in something that will keep inspiring me". That was my ethos and I stuck to it. I never buy a guitar because its fashionable, same with amps.
What do you feel you're missing? Inspiration? Tone? Functionality?
The LC15 is an alright amp, but if you feel you want to get a little more into it maybe you could save up for a proper tone monster like a Hayden or a Cornford.
http://www.cornfordamps.com/They are designed for recording and practice, the antithesis of the marshall and cabs which is for gigging really.

:lol:
Sounds to me that a good amp and a good guitar is all you need. After that playing for fun becomes more fun I reckon. :lol: