Is it just me or playing with one speaker feels better than playing with two

[Birdy]

Where do the speakers sit?

Are they mounted flush to the wall, are they on the meter bridge of the desk, are they on a table? Or are they on speaker stands (close or far from a wall)?

And what do you mean by a “dead“ room? That could mean a lot of different things to a lot of different people.

I would be truly surprised if your room is really dead e.g. an anechoic chamber.

On very thick acoustic foam, on the table maybe a foot from the wall (can't get them any further), a lot of rock wool acoustic panels on that wall.

 

[Andrew Male]

Phasing issues? If you've got a mono signal then playing through one speaker is fine. Hell some major touring productions have been mono.

 

[∞Fractals]

Hard to say; early reflections is a common one ie comb filtering - even signal chain issues could cause phase problems - poor crossover design in your monitors can cause phase issues.