It's fairly cheap to actually get a great sounding simple software setup.
Head over to Eventide and pick up their free this month "Ultrachannel"
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Watch the videos to figure it out. Parametric EQ, and two different compressors. It's amazing.
For a host try out one of the donationware hosts like vsthost
http://www.hermannseib.com/english/vsthost.htm
Or even lighter weight try Savihost - it will take a single VST and run it as a standalone application. Super simple.
The low cost USB interfaces are better than most would believe.
Or
Most laptops actually have decent sound cards built in. It's just that a standard bass is not line level, or mic level - it's in-between, so you might need a pre-amp to match levels and impedance. No need to go overboard, it's just to match levels. And an adapter cable.
If your interface or audio card doesn't have ASIO for low latency then use ASIO4ALL. A lot of standard windows drivers (WDM/KS) are now low latency anyhow.
Put it all on a thumbdrive and plug and play.
It can be as simple as this, or as complicated as running full out DAWs. Amazing what a simple PC can do these days.