If you really used a cut-, not a shelf filter EQ - with no success, then it‘s the other type of DC problem:Well, I got really excited about this theory as it seemed entirely plausible and ran to test it out! Unfortunately, that seems not to be the case. I had to set the EQ to cut everything sharply below 750 Hz before dropouts started to diminish in frequency, but they were not gone entirely. In fact, the limit of -11db where dropouts never occur on the A70 remained there even regardless of that brickwall EQ - i. e. with or without that EQ going past -11db is guaranteed to give me dropouts on a certain song.
It looks like the "HP DC abnormal" that only appears very rarely may be related to those subsonic frequencies, but overall the issue lies elsewhere.
Topping A70 must have a DC offset on the output and goes crazy when trying to push lots of DC current through Ti1a/b.
If you (or a friend, …) has a Volt meter the DC can be measured.
In this case a blocking cap between Topping and Ti1 would help.
Or maybe it’s just a general, load-impedance related, amp-instability past volume position -11 dB, - such things exist.
You might try to stay below this mark, and drive Topping’s input hotter to achieve more volume.
Last edited: