Preamp/Integrated with Loudness button

My t+a has adjustable loudness 

The Lyngdorf TDAI 3400 does everything including room correction, it’s comes with mic and stand, it sounds superb and has bass & treble where you can set the effective frequency, plus multiple preset ‘voicings’ and the ability to create your own. Very comprehensive, very flexible, very cheap for what it does.

I prefer to have a simple push button 'Loudness' ON/OFF solution. Don't want me to customise it. For that, we could use 'Bass/Treble' control or even go for a miniDSP. I have an Yamaha entery level integrated. The variable loudness switch is almost useless for me. It doesn't give the desired 'punch' the way I get from, now retired, B&K pre.

I think the best bet here is Luxman & we should thank them for keeping the legacy.

Check out Vincent Audio Preamps and integrateds. Sold by Audio Advisor.

+1 for Vincent 

I also have the Loki ... all my components are temporarily jammed into small apartment bedroom with no flexibility in speaker placement.  The Loki is amazing.  At $150 bucks it's a quiet, convenient way to improve SQ in an impossible situation: highly, highly recommend.