Preamp with headphone out

Hi all,
I'm a bit of a noob to all this, but I have just started playing live with a folk band (I play cello) and I'm having alot of trouble hearing myself through the monitors as the cello tends to get lost in there. I'm looking for a preamp that has a separate line so that I can send a line to the PA and take one for a headphone for myself. Ideally I would like a preamp/compressor/EQ rack somewhere around the £300 mark.
Any suggestions would be greatly appreciated.
Cheers,
Bill

So your cello is amplified? Or is it mic'd into the PA?

Hi,
yup it's got a pick-up. I use either a Realist pezio or The Band on either cello.