Loud popping noise with Classe Audio SIX pre-amp in phono MC mode

Impressive self reliance!  Good to hear up and running.  

Thanks! Glad it's fixed.

the 4,7uF were exploded , don´t ask me why .But there were no left over parts in the unit, I think this happened to the owner before.The replacement of the other Electrolytic caps are more a general overhaul (more than 25 years in use)than a defect. I have not much trust in the blue philips caps so I replaced the most by roederstein capacitors.I´m working as technician for Lufthansa and repair cabin electronic, former Ißve been working for Kenwood and Akai.But with I am very unexperienced with problems like the popping noise only in MC mode.Never had  a problem like this before with all the amps I repaired in all the time. Really strange ....

Forgive my inexperience but how did you know they were defective? 

Hello,
sorry for my late answer and have many thanks for your help.I opened it last week and noticed that 1of 4 Capacitors (4,7 uF /63V ) between GND and TT GND were blown.Yesterday I replaced all 4 caps and all Caps 4700uf (blue Philips Type) with new ones(Roederstein) . Today I will test it out.You´ll here from me soon.

I agree with pops,  I had a similar problem with an older McIntosh pre amp.  The problem seemed to go away after it got warmed up and it turned out to be a loose solder joint.

Could be resistor, cap, or loose solder joint.  Nice preamp, do you have someone who can work on it nearby?  Most likely an easy fix.

Sounds like a cap is going bad. 

Dirty volume control?