Iv just gotten a nice little EQ pedal, some cheapo Artec thing from Korea, true bypass(so they say...) 8 band with 15dbs of cur and boost and an overall boost. £40 delivered and its not a tone sucker to my ears, which aint saying much since I was born practically deaf in the left ear and i have abused my right ear with 15 years of live music at the correct volumes
I have tried it in front of the amp and in the loop and its okay in front but way more powerful in the loop, I guess if you have a guitar with a certain tonality you dont like you could use a pedal to eq it out in front of the amp but if you want to affect the whole sound the loop is the way to go.
I tried a MXR 6 band eq in the 3channel of my VH4 just for fun and i was surprised.Right now i like the natural sound of the more but maybe for 2nd or 1st channel just kind of a boost.
I tried MXR 10-band EQ with my VH4 and it worked well. I prefer it after the preamp, because it has much more radical effect than if used before the preamp stage. ...but to be honest, I absolutely find no use for it with this amp.