New Dedicated Line - Almost No improvement

Wow! I can certainly understand why you’re disappointed. One solution would be a system (conditioner/uninterrupted power supply) which employs a battery such that the AC for your system is generated from the battery’s DC power. Another item you might try is an isolation transformer which will cut down on a lot of the EMI, line noise and spikes/ surges just by virtue of its being a large inductor. Just some thoughts off the top of my head. I know such devices exist, but I can’t recommend specific products.

Good Luck, mean it.

The idea would be to run several dedicated lines one for each or similar pieces of equipment. Dedicate for digital and so on. 

No need for a dedicated box this just adds another break in the line.

Some have told me that stranded wire works best.

I am not a fan of conditioners or similar as they always, in my experience, took away as much as they gave. I do have very good power however.

need to look at your panel, you want if possible to have the dedicated line on the opposite LEG of the panel from motors; AC, Freezer, Fridge…. Start there….

Laynes, in my previous home, I had a 20 amp dedicated line for my 2.1 system amp and a 15 amp dedicated line for my front line equipment and surround amp. I used a Running springs audio power conditioner for the 2.1 amp. I recommend line conditioning. I also had upgraded, audiophile electrical sockets and upgraded power cables. It blackens your backgrounds. That was the main difference i heard. My audiophile pro recommended the Running Springs Audio because it does not limit the flow of electricity—it just corrects it as it flows through it. Many “power purifiers” tend to limit the flow of peak power, causing clipping of dynamics. So read up on HOW your line conditioner works. I would definitely not put two powerful amps on the same conditioner as well, even if it has two plugs, or 8 plugs or whatever.. And don’t put your frontline equipment on the same conditioner as your amp. My two cents, passed along from my trusted pro.

Here's part of an interesting article that was published in the fall 2000 issue of 'The Audio Critic'.  It puts a different spin on line conditioning:

Just about all that needs to be said on this subject has been said by Bryston in
their owner's manuals:

"All Bryston amplifiers contain high-quality, dedicated circuitry in the power supplies to reject RF, line spikes and other power-line problems. Bryston power amplifiers do not require specialized power line conditioners. Plug the amplifier directly into its own wall socket."

What they don't say is that the same is true, more or less, of all well-designed
amplifiers. They may not all be the Brystons' equal in regulation and PSRR, but
if they are any good they can be plugged directly into a wall socket. If you can afford a fancy power conditioner you can also afford a well-designed amplifier, in
which case you don't need the fancy power conditioner. It will do absolutely
nothing for you.