2 x 12 vs stereo montors


I recently bought a very nice Marshall DSL100H Guitar Amp Head, and I'm thinking about just buying or building a 2 x 12 enclosure for it because I live in an apartment these days and don't really need that huge sound of a 4 x 12. For that matter, I took the head to my amp tech to get it checked out, and he plugged it into a pairr of 15" stereo speakers and the entirety of his 1.5 story 2-car garage COMPLETELY lit up like crazy. I've never even played thru a 2 x 12 cab. Any thoughts? Many thanks.
Guitar cabs are in reality, an effect. They are, unlike studio monitors, designed to NOT reveal the truth but produce a certain sound. Guitarists spend hours discussing the merits of a brand, and then a size and then the colour of the label on it - discussing how it enhances their sound, yet spoils their colleague's when he uses he XYZ guitar. They are an audition product. You plug in and like it or hate it. We buy studio monitors to reveal more of what we actually have, and often then complain about the guitarist's equipment because to our ears, it sounds horrible, but in the context of a mix, hopefully positive.

If you want to try a 2 x 12" fire away, but remember it has nothing whatsoever to do with volume. That's a knob scaled 1-10 (or 11 for extra fruitiness) Neighbours will hate any 1,2,4 or even 8 way cabinet when you are shredding!
There is as much to cabinet design and speaker selection as there is to amp, guitar player, and desired tone.

As Rob stated, the speakers and cab you play through are also a big effect to the tone you get live. And then recording can have other needs as well.

You are likely best trying cabinets with 'YOUR' rig and gear. Find what works best for your combination and style.

Building a cabinet for whatever speakers will be luck of the draw at most. Unless you really know what you are doing and build to exact specifications (if you can find them), you still need to know what the result is going to be. Or maybe close to the result you wish for. It could and likely will be a waste of time and money.

Just my opinion.

I have built many copies of 2-18" folded horn PA subwoofers, wedge stage monitors, and bass guitar low end cabinets. Those are quite different animals though. There is more there that deals with optimizing porting and getting the best results from the driver itself.

With a guitar cabinet, it is less about efficiency than it is how the speaker reacts to what it is given. The wood, the construction, the damping, the speakers all play a part in the sculpting of a guitar tone. Hence being an 'effect' on the tone you are looking for