Tone controls?

Here ya go!
https://www.schiit.com/products/loki

+ on the loki

SAE made excellent equalizers.

+3 Loli...

Best to insert the EQ to tape loop, this connection can put the EQ out of circuit path if not in use.

Or connect the EQ between the pre and power amp, use the switch on the EQ to bypass it if not in use,

I have always thought that bi-amping or tri-amping with a fully adjustable high quality active crossover was a far better solution than tone controls. It;s just not doable with most systems, or prohibitively expensive. 

Speaking for myself, I really only use tone controls (if I have them) at low volumes. Most of the time, flat is where it's at. Otherwise, adjusting speaker positioning, dealing with room reflections and sitting in the sweet spot are the way to go. 

+4 and +5 on the Loki. I have 2 of them in 2 systems and wouldn’t go without now.