I've got a Traynor YCV40 amp, with stock tubes (Sovtek 5881 WXTs) and stock 12" speaker (Celestion 70-80). From my understanding, the tubes and speaker are both pretty mediocre compared to whats out there.

I've been noticing that the lower end of the amp starts to sound terrible with an increase in volume, particularly when the tubes start to break up. Mids and highs still sound quite good, but the lower end of the register just sounds muddy, almost like the speaker can't handle it. Everything, even bass, sounds great below 10 oclock, at lower volumes.

My question is, is it likely this mediocre speaker giving me troubles. Its a 40 watt amp with an 80 watt RMS rated speaker, and a low end frequency of 80hz. Is it the speaker? The tubes, be it due to them dying or just their quality? All of the above? I'm considering upgrading all of these at some point, but just curious what will help address my situation. Thanks
Nothing intense, just blues type riffs and what not, bass is set at about 5/10, so its not cranked by any means
could be the tubes depending on how old they are.
coud also be the speaker.

it's hard to say without hearing it.

There is a certain amount of flub in the bass with power tube distortion.
Prs se Holcomb is the answer
Yeah I hear you. This "flub" seems a bit excessive though than it should be. Tubes are probably nearing the end of their life anyhow, probably worth replacing anyway