[drvolks]

Something that might help new owners of this headphone amp / pre-amp.

First, the ground loop. This has been mentioned on head-fi and other review sites. There's a constant hum audible even at normal, listening, volume. For me the trick of removing the ground pin on the power cord did not help much. But then I bought the ground loop isolator at Radio Shack (# 270-054), plugged between my TCC input switch box and the Little dot input line and... yes indeed the hum disappeared!

Second, I had a intermittent high pitch sound on one speaker. A very annoying sound! I tried to swap the tubes, change the cables, nothing did the trick. Well this week I decided to order some tubes on eBay to hopefully solve this problem. I'm glad to report that it did solve the problem! The sound is incedible... Like any audio upgrade the placebo effect is very enjoyable

I followed the tube information in the little dot owner manual and ordered this following tubes:
M8100/CV4010/6AK5W MULLARD NOS

30$ including shipping. A very good investment.

Hopefully this information will help others.

 

[Caribou679]

I too had noise + hisses. Brushed contact cleaner on the tubes pins and it corrected the noise.

regards,

 

[rohanjd]

Thanks drvolks. Planning to buy the MKIII, to work with my K701s.

 

[robbmcaulay]

Thanks for the post. I have a little hum in my mkIII and I think i'll buy a ground line isolator.

D'you know if the signal wire has to pass through the box, or just the ground? I'd like to make a cable that allows the signal to bypass the box to keep quality.

 

[Pricklely Peete]

Caig Pro Gold is amazing stuff. I use it on all my tube pins and IC's contacts. Gets rid of all kinds of hiss,hum,pops etc...it's cheap to boot.