I have a 200s head that's been mothballed for over 10 years while I played the mandolin. Having seen the light, I'm getting back into some electricity, and I'm wondering if I can use this amp with a speaker cabinet rated at 4 ohms. The 200S has 2 output jacks labelled "8 ohm speaker" and "4 ohm external speaker," and I suppose the obvious answer is to use the "4 ohm external speaker" output with my 4 ohm cabinet. Is the obvious the correct choice here?