Extension cab - advice sought

[Guest MoJo]

I recently purchased a Peavey BAM210 from a fellow BC member and am thoroughly happy with my new acquisition. Considering it's a fairly compact 2x10, it seems to shift a lot of air and have plenty of low end response. I'm certain it will hold it's own in an average pub gig.
For larger venues without PA support, I would like an extension cab. I used my 4 ohm Schroeder last weekend with great success but, me being me, I'd like the cab to match the combo. This gives me three options, the 4 ohm Peavey Pro210, the 4 ohm Peavey Pro410 or the 8 ohm Pro115. Ideally I'd go for the 210 to match the the 4 ohm 2x10 drivers in the combo but, the 210's seem very rare. My concerns about the other two cabs are that the four drivers in the 410 will only be working half as hard as the drivers in the combo and the 8 ohm 115 will only be getting about a third of the power from the amp, the other two thirds going into the efficient internal speakers, rendering the 115 almost inaudible. My other two options are to buy the 115 and swap out the driver for a 4 ohm equivalent, suitable for the cab or stop worrying about how things appear and stick with the Schroeder.
Your thoughts please.........

Edited March 28, 2014 by MoJo

[xgsjx]

First thing to identify is what the minimum ohms is for the amp in the combo?
If it's 4 ohm, then adding a 4 ohm cab is going to do damage. If it's 2, then chances are the combo drivers are wired to 4 ohm & you may want to add another 4 ohm cab.
Your concern about the different cabs is valid, & a matching 2x10 would be the advisable choice. But if the amp is 2 ohm & the combo wired to 8 ohm, then the 4 ohm 4x10 would mean all 6 drivers are getting equal power.
If you don't go through a PA & have foldback, I'd say get the matching cab & put them vertically for improved dispersion.

[Guest MoJo]

Minimum total impedance is 2 ohms

[xgsjx]

It would be easy to surmise that the combo drivers are wired to run at 4Ω, but that's not a given.

[Guest MoJo]

The combo is 4 ohms (two 8 ohm drivers wired in parallel) with a single extension output socket, minimum load 4 ohms

[Truckstop]

Just have to hold out for a 2x10!

Truckstop

[Bill Fitzmaurice]

[quote name='MoJo' timestamp='1395993413' post='2408649']
The combo is 4 ohms (two 8 ohm drivers wired in parallel) with a single extension output socket, minimum load 4 ohms
[/quote]You want a 4x10 that's half the impedance of the 2x10. Obviously that's not an option, so a 4 ohm 2x10 is your best bet. But that still gives you four tens total, and the difference between that and six tens isn't all that much.