I cant tell you the sound difference between series 1 and 2,,although id assume they sound the same. There are some differences with cosmetics and functionality but sound wise I dont know.
I have found the effects loop on my series 2 combo to work quite well.
I am running a chorus and delay pedal through it now and they both seem to work well. In the past I have run 2 different eq pedals in the loop and they both sounded fine. The only issue I ever had so far with the loop is when I would boost the eq's up high in the bass frequencies I would get a weird thumping noise out of it. It seemed like they were overloading the circuit or something. I also owned an MXR M109 chorus pedal and it had a bass boost button on it,,,when engaged it would cause this thumping sound. Again it sounded to me like maybe an overload.
I wish somebody could tell me why exactly that happened.
One more note,,at the time I owned some of these pedals I had a
EH 12AX7 in the loop tube spot 4. I used these there because I thought they seemed to cause too much feedback in my gain spots. Maybe those tubes were a bit too high gain for the ciruit,,,dont know. I have recently changed that v4 spot with a standard jj12ax7 and havent had any issues.
Now I have to try an eq pedal and boost the bass up high
