How old is your SG Standard? The newer ones have the '57 Classic, but the older ones had different ones. I personally really love the '57s and think they sound great (especially through the Mesa amp!). So if your guitar is an older one, I would suggest the '57. If you already have those...
I had recently purchased a JVM215C combo, and I had the same issue with it - it was really noisy. I especially had a problem running the Noise Suppressor pedal in the Effects Loop. I got some good tones out of it to be sure, but I couldn't get passed the noise.
I then tried a Mesa Express...