From what many Ampeg lovers have said in the past, it's very close to sounding like an 810, except you need to bump the bass knob up just a little to get the low end to sound the same. The cab is a little smaller than 1/4 of an 810E. It is a tweeterless, sealed cab like the 810E. The 810E has drivers that are further off the ground, and closer to your head, and that will sound different than a single SVT210AV. 4 of them will be 8 ohm in series parallel wiring, or 2 ohm in all parallel wiring. Not sure how loud 4 of them will be compared to a 810E, but I would assume pretty close. 2 is decently loud.
Wes