personally, any inexpensive combo is inexpensive because costs were cut somewhere.
Usually the 2 most expensive parts of a - tube - combo amplifer are: (yes, obviously
PCB construction etc also enable lower production costs but we're talking about
the parts used -- even so-called 'hand wired' amps can cut costs using cheaper
components)
1. Transformers
2. Speaker
and that's where the bulk of costs are usually cut to be able to
get to a low retail mass market price point.
So... keeping that in mind... in a tube amp - LOOK FOR BIG IRON i.e.
look for big sized transformers -- this is usually an indication that at
least some nice transformers were used for the amp which means that you (usually)
can expect to do a speaker change and the amp will be all set to go to sound
nice. (again - these are my own personal feelings on cheaper tube amps).
The thing is that no matter what speaker change you make - if the amp uses
small cheap transformers (which also usually means that the bass on the amp
is attentuated and rolled off at 120 Hz - 150 Hz or so) that you will never
get a nice tight low end or any sort of bottom end on the amp.
Look at classic Fenders... the Vibrolux gets its sound mainly because
it used wimpy transformers which means when it got cranked up the bottom
end and eventually tne bottom mids started to flub and go away which let the
mids and upepr mids and treble be the predominant tones... the thing sang
and screamed... but when cranked up just can't 'chug' or have any bottom.
but that's the charm in it. People sometimes change out the transformers
for beefier ones and lose that unique Fender tone... yes, the amp gets a more
modern sound... much bigger bottom that stays tight... but it's not that
original Fender sound. And it's due, in a large part to those transformers
which Fender cheaped out on and serendipity kicked in and created a unique sound
which people got used to over the years. But yeah - those cheap cost cutting
transformers were the thing.
Ok - back to current times -- look at the "Tiny Terror" head and then look
at the Mesa/Boogie Mini-Rectifier head. The stock Tiny Terror uses wimpy
little transformers and has no real bottom end to speak of and to mask that
they use lots of attentuation on the bottom end roll off (its attentuated to
around 150 - 200 Hz to mask the fact that it can't handle, in any sort of tight way,
lower tones or bigger wave forms). So yes - the bottom sounds tight but
it's thin. Look at the Mesa - huge transformers - and it also uses EL84
power section - but the response goes down to 80 Hz - big tight bottom end.
It's those transformers again that allow that. Mesa didn't skimp.
You can use any speaker you want with the Tiny Terror and it simply can't
get you the big bottom end -- cheapie transformers and low end attentuation in
the preamp circuit assure this.
So... LOOK FOR BEEFY TRANSFORMERS first and foremost. At least you have
big iron in the amp. At least look for an inexpensive tube combo that the
transformers look larger and heavier than a tone control knob.
Based on this I would recommend:
Peavey Valve King -- you can pick these up cheap and it has enough
power to play anywhere. Run pedals through the front end on the clean
channel and you're all set to go. However - a speaker change is a MUST.
I suggest changing the speaker to either a ceramic Warehouse Guitar Speaker British Lead 80
or (if you want to lighten up the haul) Jensen Jet "Tornado" speaker.
Both are excellent and match up well with this amp.
that's my take on all this for an amp that can do big cleans
and has a usable second gain channel (which on the Valve King won't
get you until uber metal...) and has the power and punch to play
live anywhere even with a heavy hitting drummer.
I recommend using the clean channel on this amp as a pedal platform
and kick the pedals off and you have a huge clean channel with lots
of headroom.