New Octal VTA-70 hiss question

Hi, I just completed building a VTA ST-70 with the blue Octal board. Or more specifically I replaced a Erhard driver board with VTA and SDS cap board.
On the bench it biased perfect and was dead silent playing music from my phone into a pair of Realistic speakers.

I brought it down to replace the Curcio ST-70 in my living room. Only change is one modified dynaco for another. The rest is Amazon echo link as source directly into the amp as it has volume control. Speakers are Spica TC-50.

I connected it all up and let it warm up and checked the bias. DEAD silent! Then I played music and I got a windy hiss from both speakers even when I stopped the music. When I powered off the amp the hiss picked up in volume and then faded away as the power dissapated.
Not ground loop, but I lifted ground just to be sure.

Removing the link and connecting an ipod resulted in no noise. Back to the Link and noise again.

Having seen threads about preamp matching, I inserted a spare preamp (Acurus LS-11) between the Echo Link and the amp and was back to silent play. No hiss, just music.

So, knowledgeable people, did I miss a step with the new board? Or is the VTA board more sensitive than the Curcio one? All things equal why is the preamp now necessary in the signal chain?

Heading out on vacation, so no rush on answers. Next week I can try any suggestions if there are any.
And by the way. Ultra HD streaming through the Acurus, VTA, Spicas is a beautiful thing.

What exactly is the nature of the noise? Is it random noise ( as in between FM stations ) or
is it hum ?
Is the outlet where the amp is connected grounded ( 3-prong), does the amp has a
3-prong mains cable ?

It is a constant shhhh like interstation white noise.
The amp is plugged in to a filtered power strip via a three prong grounded plug.
I've had issues with ground loop in the past so I tried lifting the ground but that made no difference
The Echo Link is two prong. The preamp is three prong grounded.

Thanks

I have no clue, am unfamiliar with Amazon echo link

That is really strange. No, a preamp should not be required for either the ipod or the Echo Link line level RCA outputs based on what I see listed in its specs. Is the hiss equal in both channels?

it seems pretty obvious that the hiss is coming from the source, not the amp.
You say the amp is dead quiet until you connect to Amazon Echo, or to one preamp.
And it's dead quiet when connected to a different preamp or when connected to an Ipod.

The thing that confuses me is I don't have an issue with the other Dynaco. I'm wondering if it is related to output voltage or the source and possibly the Echo is higher than the Acurus.