whats the very best sounding cables for realistic money

for AC power bottle head cord or better a Topaz isolator

for DC power to a USB DAC, use an isolator/regen device and a LPS for best results (which may be zero depending on your DAC etc.) - wind up a DC cord using a star-quad layout or buy from Ghent

for speakers, use short runs with mono-blocks and try various cheap cables until you like the effects of complex impedance changes

for ICs, use balanced

all the above are inexpensive and effective - shills, fan-boys and fraudsters will try to sell you ineffective things for thousands

I'm late in responding, but I have built @williewonka 's designs that he posted and they are amazing cables for my system. I've made helix ICs, PCs and SCs. You can choose your own conductor, which is nice. Tailoring your cables to your system and desired sound is an amazing freedom to have. I love silver, so have used it throughout my cables, but you could go copper with gold or silver or rhodium.. the sky's the limit. 

To my ears, the cables I've built are very quiet, very detailed and neutral.

I love building stuff, but if you've never built cables before, these aren't too difficult to make.

It looks like the OP is from Great Britain. The voltage there is 250 I believe, and has different wall outlets. So many of the smaller American companies would not have power cables suitable for this chap, but various RCA and digital cables would be fine, and of course the bigger manufacturers market appropriate power cables in Europe.

The first RCA cable design that blew me away was one employing solid wire conductors instead of the more common stranded wire. Small solid core conductors that are individually insulated prevent the signal from jumping from strand to copper strand, and the result is quite striking. Audioquest, Wireworld and Morrow Audio all employ this basic concept, albeit with different approaches.

For lower cost, Morrow is my favourite. Each solid copper conductor is silver plated, and then insulated. Their entry level RCA IC is the MA1, and it has 2 conductors. The higher you go up the line, the more conductors are employed. The M3 has 12 runs, and for me is the point that depth to sound stage is noticed. The MA 1 has no depth, just a 2D stage, but still images well.

The pricing has various discounts available, and is sold directly from their website. One needs to have the solid core insulated conductor design as a complete loom, or else the signal gets compromised, although the power cables don’t seem to affect things, at least in my experience. I at first did not have solid core speaker cables, and the improvements with only RCA cables was not as striking.

My first speaker cable of this design was the Audioquest Type 4. One doesn’t notice the compromised sound and think something’s missing. But replace the cables and the difference is not subtle. But don’t try this with 30 or 40 year old vintage equipment, or the typical AVR either.

I like Purist for realistic money they sound great as well

Go studio way and get the Gotham 2 x 6mm speaker cables. After trying many cables this is the quietest, cleanest and most unvoiced speaker cable I could find. It does not have its own sound that I could detect.
http://gothamcables.com/en/gothamcables/speakercables/50260frnc2x6mm

Townshend cables

I had some PWB Electronics speaker cables along with TG Audio speaker cables for my bi wired Fultons. The PWB cables are very good and quite exotic but affordable. Dunno if they still sell cables but they might.