Classic SVT-VR 300 watt head, one 8x10" cab, and one 2 x 15" cab, and an Acoustic B200 as a (personal) monitor Works fine.
I picked up a peavey tx 410. That SHOULD handle it. Guitar players are using a combo amp or 212 cabinet. Drummer isn't micd, so we have to watch our volume anyway. I just know last year, the acoustic 410 didn't handle it well. I played the acoustic until it started distorting. Then unplugged it and plugged in the peavey. It had a lot more to go and still never got distorted. It just eventually stopped getting louder.
Two stacks; each consisting of an Ampeg SVT-410HLF and an SVT-210HE on top of it. Powered by a QSC PLX 3602. Each stack is louder and deeper sounding than the regular SVT-810E I have used.
It depends. I have a few different ways I can go. If we're the solo opener before a headliner I'll drag out my SVT and 2 Hartke 410XL cabinets. Otherwise I'll bring out either the SVT or a Sunn 1200S and a Hartke 410XL cabinet loaded with 4 Eminence Omega? 500 watt speakers.
The Peavey with the GK mb500 easily got the job done. Even at 8 ohms, it had more than enough juice to get it done. I love the sound of that GK with that bassy cab. All weak links in my gear have been eliminated.
If your 2x10 is 8ohm and your 4x10 is 4ohm then they'll play nicely. You just need an amp that doesn't mind the resulting load.
My band's volume is what I would call "medium." No PA support, usually. Indoors I use an SVT and two Mesa TL606 115s. Outdoors, I would bring two more.
I did tons of stuff outside all last summer with and acoustic b410 and a line6 hd 750. (Weird rig, I know. I bought the pieces in a jam when I had a problem) The cab was 8 ohm so the head was only running at about 375w. This rig throttled outdoors. It sounds to me like your head is just under powered with the 8ohm cab. I know acoustic has a bad rep around here but a cheap (I guarantee it would be hugely effective) solution would be to just add another identical b410 to the rig. You will get the coupling effect and pull more power out of your head at 4 ohms. I personally was very surprised because I just bought the b410 cheap in jam and it turned out to work great for me. I have since sold it but only because I got my svt rig. I would recommend it to anyone though.
For medium size outdoor gigs with no FOH support I find my Bergantino AE410 works just fine. For a larger crowd, I add a second AE410. I have only done either of these once or twice in the last couple of years.