I have a jolida fx2 dac.

Just bought some raytheon 5575 valves off these forums and adaptors off ebay.

Used for first time today.

1) Left channel - has bad hum increasing with volume.
Right channel - sounds good.

I swap over the valves (not the adapters).

2) Left channel - sounds good.
Right channel - no sound at all from speaker.

I swap valves back and forth.
Each time i swap, it goes 1) 2) 1) 2).....etc (above)

There seems to be one good valve.

The other valve seems to have problems as when in one channel it hums, and when in the other channel it looses sound altogether.

I have repeated this 6 times.

Valve problem?

Or am i missing something?

Thank you.