Is this do-able???

[sykilz]

So I`m in this quandry, I run a Hartke 210 combo 250 watts, and need a bit more oomph.The amp won`t let you use an extension cab as it`s own speakers are 4 ohm and it runs at minimum 4 ohm, I did consider using the head out of the combo into a new, larger cab for larger gigs and using the combo speakers for practice, but this seems a bit of a waste of time. Now I`m wondering if I should get a powered sub to run from the line out of the amp, thus using the amps speakers and an additional 15 or 18 incher???? Of course the sensible thing is to sell the combo and start again, but I like the tone and the portability of it, and frankly I`m not overly burdened with cash at the moment. Anyone tried this idea with success/failure???

[JTUK]

Not a fan of this idea... and am not sure whether the line out is pre or post to run the powered sub..

I guess you need to try it but I wouldn't throw any cash at that process ..try before you buy..

If you run another cab then that rather destroys a portable argument..but you may have to do this..

If the current cab is 4 ohms then that implies the speakers are 8...you could wire them to run 16 and then put another cab in the mix, but this is pretty clumsy.. and you are cutting dowen the output when just using the 2x10 by some way, I think..

I would set the ball in motion to trade up the combo for more power... or more flexible outputs so you can add a cab easily..

[Tinman]

You can but I wouldn't.
I did a similar thing once when all I had to gig through was a single 12" GK 100W combo; it sounded awful. All I got from the sub was mush.

A more powerful/flexible combo is the way forward.