melos sha-1 problems...

Hello everyone,
i've got this pre-amp recently but it has got a big problem. could you guys please help or give advice?
when the first time i hook it up i found it takes more than 5 mins to warm up and after that it comes out with a hiss sound even though i turn the volume pot all the way down. when i turn it up to around 2~3 o clock position it turns from hiss to a big "wooooo" sound, the sound is so big that i can see the speaker cones are moving... so i change all the caps to a better ones(same value) except 2 of the 6uf/250vac and change the volume pot to a DACT step volume. change the tubes to jan-philips 6922. but still the hiss is still there. the worse is that when i connect it with my other melos cd player(with melos d/a) i can hear the sound when the player scanning the cds(from the speakers) please could anyone help since i live in hong kong so not much people can help me this nor getting the caps (6uf/250vac). anyway below list is gear i'm using now.
cd: melos cdtII with melos cd player(sony mod)
pre: sha-1
power amp: aragon 4004 mkII
mon: adam anf10
power con: lightspeed 3200 mkII
all gear using bleden 18awg dbl sheilding power cable
inconnect using canare cale
speaker cables using hitachi melltone(the pink ones)
many thanks!!
Why not give it to a reliable tech. Sounds like you`re in over your head. Changing caps & tubes doesn`t solve every problem. Test equipment & expertise are probably needed.