Upgrading audio interface

[Jonno02]

Hey guys, looking for a bit of advice.

Right now I'm running 2 KRK RP6's with an Alesis io2 express interface. I've just picked up 2 Yamaha HS50m's as a second reference and want to upgrade my interface as the io2 only has 2 1/4 inch jacks.

I'm looking for something with 4 1/4 jacks so I can run both sets of monitors at the same time and if possible with an "A/B" switch.

Price range is about £100 - so very modest. The alesis io4 looks good for the money and does what I need, but I'm very uneducated in this area of hardware and was looking for some help with someone with more knowledge.

Cheers for any help, appreciate it a lot!