A15MK1 troubleshooting help

I've just finished building this kit...and I have some questions...here they are:

1 )The amp is a bit noisy in clean channel too with no volume...if I turn up the volume some more noise comes out from the speaker (like frusshhh frussshhh it doesn't seems 50Hz) even if the guitar has the volume turn down...what I have to check to get rid of it? And I think is related to this if I touch with my hand the clean channel treb pot this noise increase...is it a ground problem?
Of course the noise increase in channel 2

2) It seems that at low volume the channel 2 ( ++ switched) has few bass...and seems a mosquito...any issue or just because the volume is so low?

3) what is the function of the smooth switch (no explanation found so far)?

4) Have I to put the shield on the tube or can I leave the tube without the metal shield on them? (if yes on all tubes or just on the Pre amp?)

5) any additional check I can do to find and assembly mistakes? (the voltages seems ok so far)

Thanks a lot MAD for this kit!
Krusty

Re: A15MK1 questions

1) I have double checked 100 Ohm resistor doing the soldering again on power supply board but the ffffsss and the zzzzzz still comes out from my speaker...:((( any other suggestion? I think this is the main problem with my amp...is it possible to have some audio sample of a A15MK1 amp (all channels) with all the pot open (all to right) to hear how much noise should come from a well assembled amplifier? (this is my first one)

2) is it normal that in channel 2 if I raise the gain a lot I hear the sound coming out from the speaker even if the volume pot is completely closed? it seems strange to me...but as I told you i'm a novice and still trying to learn...

3) my amp seems always to lack on bass freq on channel 2 and channel 2 boost...have to use smooth mode to mitigate the high frequences (at low volume)...any suggestion?

Thanks a lot again!
Krusty