They work equally well with solid state and tube amps. Just like any pedal, some work with certain amps better than others. If at all possible, try before you buy, or at least make sure that you can return the pedals for a refund in case they don't work well with your gear. Also, just because it's got a tube in it, doesn't mean that it actually gets any added tone from the tube, and doesn't mean that it will sound "tubey", and doesn't mean that it's any better than a similar non-tube pedal.