Extension Speaker Cab question

[foreverstrung]

My OTS50 clone I built from a Ceritone kit has the speaker jack and extension speaker jack wired in parallel. Normally I have the impedance switch set at 8 ohms for the 8 ohms EVM12 speaker cab I have. Now I've got an additional 8 ohm EVM12 speaker cab and if I plug it into the extension speaker jack, I should set the impedance switch to 4 ohms, correct? Or will I be fine just leaving it set at 8 ohms. I understand that running lower ohms is usually ok, but since I have an option to set it at 4 ohms, should I use it?
I'm attaching a pic of the speaker jacks portion of the layout diagram to confirm I don't have my head up my ass and these jacks are wired in parallel.
Thx
Dave

IMG_2631.jpg

[xtian]

Balancing the load will get you the most power output. So, two 8 ohm speaker cabs wired in parallel makes a 4 ohm load, and you should set the selector to 4 ohms.

Sure, you can run a mismatch if it sounds better to you. You'll get a bit lower output, possibly earlier distortion (but only if you're pushing the amp hard, that is, LOUD).

[Stevem]

Running a mismatch ( 4 on a 8 for example) will also eat up your power tubes faster and change the overall frequency response at the extremes .