15 foot RCA cables out of TT with no pre amp?

I would listen carefully to a very familiar lp with distinct lows, mids, highs. Then make a temporary short cable hookup, listen, despite theories, I doubt you will hear a difference.

let us know if you try this.

Hello,
Most brands of TT have less than 1 meter of cable coming from the cart. I would recommend Shiit Mani to start with. At $150 it is a really great product. From the Shiit Mani you can run the longer cable to an input on the Receiver. Do not use the “Phono” input if you are using a phono preamp like the Shiit Mani. You can use an empty RCA input like AUX, Tape, or VCR since these are usually open. 

Here is the link:
https://www.schiit.com/products/mani?gclid=Cj0KCQiA0rSABhDlARIsAJtjfCdVprHu9F3ss5cXroD4Olt0lBM6c1vfF...

The effect of cable length is as a multiplier of the capacitance per foot of the cable. A typical MM cart has an ideal capacitive load for flattest response. You have to know the capacitance of the internal wiring of your EVO, subtract that from the target, and divide the result by15 to know what type if cable to use. Getting this info ain’t always easy. The recommendation of BJC LC-1 with an added ground wire seems pretty sound to me. 

I failed to mention the Onkyo receiver preamp has its own capacitance. If the EVO has 80 pF and the preamp another 80 pF you need a IC with next to zero capacitance...as the target is 200 pF for Ortofon 2M. Hence the recommendations for a closer placement using an outboard phono stage.