"Even though the Bugera v5 infinium is only 5w, have you tried simply connecting the V5 to the Marshall speakers directly? Assuming the back is open.."
Bad advice. The Bugera is a 4 ohm load - the Marshall is 8 ohms. Bad MOJO!
Wait for your mixer. You can patch both in nicely.
Regards,
Bob
Come one now..... Bad Mojo? no way.
It's a 100% tube amp. pre and power tubes. You won't kill a tube amp, or even hurt it with a mismatched speaker load. We played lots of tube amp speaker load combinations in lots of bands and had no problems. We did it intentionally to get the different tonal characteristics of the mismatched load.
If the amp was solid state there would be merit to the argument because transistors are more affected by the lower impedance. But that also depends on the design of the amp regarding cooling ability.
But, if you wanted to follow the advice of Bob..... just put 2 marshal cabs in parallel and waaa laaa, you have a 4 ohm load.
I would not worry about destroying the V5 with a 4 ohm cab. Seriously.