Two speakers vs. one
Hopefully this isn't a really dumb question. Is there a big advantage to having two speakers in an amp compared to a single speaker? Is it enough of a difference that it should be a significant factor in my search for an amp?
Here is an intro on the topic. It's related to bass, but most of it applies to guitar amps as well.
i'd say the head is going to be a bigger factor than the speaker if you're getting a combo, but you always have the option of getting a separate head and speaker cab. imo, two speakers give a fuller tone than one, but it's less of a difference than different heads or different speaker brands.
Some folks like to mix different kinds of speakers.
"A cheerful heart is good medicine."
I asked myself the same question not long ago. At the end I decided to buy a single-speaker combo because it was simply easier to carry around and had more than enough power and volume to be played (only) at home. I tried out a few different amps with 2,3 and 4 speakers - and seriously considered at least one of them (Victoria 35310) - and now I regret not buying it because it had more clarity, more balance and a brighter/fuller sound.
If you are into combos, I would at least have a look at them and try a few out (Fender Bassman for instance). I found most of them far too heavy and way too loud for playing at home, but this might be different for you. They are generally also a lot more expensive.
As for a head and separate cab, I haven't really looked at that, but going down that road opens up a enormous amount of options - mixing heads and cabs, different speakers, etc.
A 2 x 12 will sound fuller than a 1 x 12. But as everyone has mentioned, portability becomes the problem. If you don't mind lugging an amp that may weigh 65 lbs. or more, go with a 2 x 12. If you want an amp that you can load on the backseat at a moments notice to go jam at a friend's house, then you will be happier with a 1 x 12. A 1 x 12 provides plenty of sound and fullness for a gig, but a 2 x 12 will sound bigger every time.
If you know something better than Rock and Roll, I'd like to hear it - Jerry Lee Lewis
It will also depend on the type of music you play and how loud you play . With country , blues , pop and most older rock styles one 12" speaker is plenty for anything short of an arena . With heavy metal I would suggest more speakers as they are likely to use drop tunings and accentuated bass .
If I claim to be a wise man , it surely means that I don't know .