I gather it is fairly simple to modify the pip phono input to balanced. (1 capacitor I think). The issue is the input to the line stage.   I have 4 scribbled schematics of alternatives, all of which fall over at the volume pot. I think if we hadn't run out of time the punch line was going to be an amplifier on the front.

And although I use it in active mode on phono since it needs the extra gain for my dynavector, legend has it passive is preferable for the line stage, and the bits of scribble are supposed to explain why that is trickier.

Again - with short cable runs and Mains not running parallel to signal (when you get your new house, are you going to set your hi-fi up properly?) - balanced shouldn't be necessary.  Noise on the interconnect should be vanishingly low. The obvious noise on the cable in the video was a scenario that was artificial (over 2m of signal cable run right next to mains cable.)

But even with the shield grounded, noise wasn't zero. It was "sufficiently attenuated". However, with the best hi-fi, what should be the threshold for "sufficiently attenuated" and what can a "properly set up" unbalanced connection achieve? I'm hoping we will (one day) do some tests.

Ironically, I got in the habit of locating the quad a decent distance from the low level signals to reduce noise from the transformer. The benchmark is quiet enough and cool enough to have the pip sit on top. And has balanced connections that would let me site it in the room next door.

Listen to two commercial examples of good design: a Gram Amp 2SE at around £300 and an Aurorasound VIDA at around £2800. Each sounds great at its price point, is well made and reliable. If you can engineer and 'productionise' a phono stage at a substantially lower price for similar sound quality, and get your routes to market sorted out, then go for it. Otherwise, you're in for a world of pain and it simply won't be worth it.

You do seem to be having frustrating issues with mains hum there! I can't say it's something that's ever caused me any trouble. Obviously there would sometimes be a change to the system which would cause an earth loop but that would take minutes to cure usually...

Sounds interesting to me..

Yup - its been the bane of my life.  The recent one has been mainly the AV.  Like all these "fault diagnosis" issues, when you know the answer, or more of it - the story never tells well because the mystery is no longer there

(The real bastard was the combi-boiler from hell - I still have a garlic string in the front of the case)

The "problem" has made me speculate about "non-problems" - ie apparantly noise below the threshold of audibility.  The problem was the AV input.  The solution basically a chassis ground to chassis ground.  Lots of stages along the way where I thought I had a ground but didn't.  Bits that have been part of the "fuss" are

The chassis ground nearly silences the hum - I would have said silenced it, but I've got fussier.  However, there were degrees of ground silencing - heavier gauge wire got quieter and quieter.  A slightly loosened ground connection would give a slight noise.  Its still not silent - but I'm not bothered about that particular input because it is for the AV watching Liverpool on Sky Sports, or Game of Thrones.  If it was my 2 channel, I would still be on a mission.  In previous ground loop situations, with shorter cable runs, it has just been a question of connect up the right 2 points and it "goes silent".  But did it go silent - or just very very very heavily attenuated?  Most papers I've read on ground loops are happy if they can drop hum 40db - 50db when they are fussy.

Although silent in normal use - turning on a light which is on a dimmer switch, introduced a low level buzz again.  I think that means a very very loud noise nuisance took the "attenuated noise" back above the threshold of acceptability.  The solution was to turn off the light, which we didn't want anyway - but it indicates how the chassis ground is not a complete perfect solution - although apparantly "silent"  (No noise breakthrough with the light dimmer on the other 2 inputs mind)

The chassis grounding shenanigans, included an "aha" when I put a ground wire from the power amp direct to the sleeve of the satelite cables on the back of the sky box, itself not grounded to the mains, but connected to the AV amp which is the apparant source of the problem.  It's too bloody inaccessible for me to have played with now it is "silent" but I think the satelite cables are a big part of the ground loop.  Odd thing is, I can't see anywhere that they are grounded, unless it is that they are a very long screen connection to the other sat receivers on the other side of the house, which are themselves grounded, via the TV's they are connected to.

Oh - and the connection from AV amp to Pip is 5m of unbalanced cable, much of which runs almost alongside mains for too much of the way.  Just pulling it out in front of the TV and across the middle of the carpet would probably have a big effect.

Anyway, I expect that has bored you rigid - but its gotten me interested in noise, and silence that isn't silent.  Especially in the context of a power amp that thinks there is some relevance in SNR's of >90db (as in 132db)

It's made me realise how much, more than anything else, all I really want is equipment that "just works".  Every time.  And kinda - at the moment - it does. 

My thoughts along the burn in scenario are:
Speakers move when playing, so they 'limber up'.
Wire does not actually move does it?
So how can wire 'burn in'?

You didn't fancy my chances with speaker cable either, and we know how that one went.

I actually agree with you.
I do not think I will be able to tell the difference between a newly constructed lead, and one of my older ones.

What happened with the speaker cables?