Not-exactly-a-newbie saying hi!

Hi all,
Was a forum member years ago, but reset my password and I seem to have to introduce myself again.

Need a bit of advice hooking up a single ended SMPS to a split supply analogue preamp and then on to a single ended digital power amp.
I’ve done all the usual things like building a virtual earth supply splitter for the +/- analogue bit and caps on the in and out to block the half supply voltage appearing on the signal, but don’t seem to be getting anywhere.

I want to try and make this out of available bits in my box……I have this great 250W class D power amp that works great with a 30v/12A SMPS industrial PSU.
Now I need a bit of help to hook up this nice preamp that’s got mic & line ins and tone controls, but wants a split +/- 15v supply.

I’ve got an op amp (LM358) generating a virtual earth and that’s got the input bargraph on the pre working, so I reckon the split supply is working OK….ish, but getting tons of noise on the opamp and no gain.
Can’t seem to get the audio grounds to agree with each other……..Any clues anyone ?
I’ve convinced myself that I’m doing something truly dumb. lol