Electro Harmonix Signal Pad

Bought this unit to act as a 'boost' for my valve amp. I really like the sound of my amp but didn't want to chain together effects or spoil the tone I'm already getting. Another guitarist who gigs regularly introduced me to using a unit like this. The principle is that you set your amp to the loudest setting you need for your solo then use the pad to reduce the overall level to your crunch /clean volume. You click the pedal on to reduce the volume and click it off to raise it to solo level. The pedal doesn't need a battery or PSU so it can't fail on you mid-gig.
This means that you can effectively use your amp alone to give you your desired tone without having shedloads of effects in the chain.
I recommend you give this a try for yourself, I doubt you'll be disappointed.