I know bigger speakers and more wattage=louder but how do they differ in sound quality? Like how would a cube 15x compare to a cube 30x in sound quality?
30W would be able to go louder, without starting to clip the powersection. With SS and modeling amps, you don't want the the amp to start clipping, or it will sound awful. "Headroom" is the term used for the amps ability to keep the signal true without clipping, as the volume is raised. The more wattage, the louder the amp can go before the powersection starts clipping.

If it was a tube amp, you might want the powersection to start clipping, as that produces the overdrive that is so coveted and sought after with tube amps. As the tubes saturate, it produces soft clipping as the waveform is compressed, and the peaks are rounded off.

As a SS poweramp is pushed beyond it's capability, the transistors hard clip the signal, which abrubtly cuts off the top of the waveform peaks, and produces a very harsh non-ear pleasing sound. You want to avoid this with SS and digital modeling amps.
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well, IIRC, those particular models are different. The 15 was missing a lot of stuff as I remember, so in this case, the 30 is much better.
"The fool doth think he is wise, but the wiseman knows himself to be a fool." - W.S.
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Quote by Hellfire999
So a cube 30 and a cube 15 would be very similar in terms of sound?

They're going to be about the same loudness.

The cube 30 will be cleaner at higher volumes though.

The cube 30 is kind of an akward wattage, it is between bedroom volume and practicing with a drummer. The cube 60 is going to have that extra bit of ooomph that would be necessary for playing along with a drummer.
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