I need a loudness switch

My Accuphase integrated has a loudness button. I know they make audiophile purists cringe.
Right now I am listening to Someday My Prince Will Come, CL1656 six eye. 55 decibels from my chair and  I would rather follow Paul Chambers bass line than be pure.

I have considered the low 2.2 v output of the Soundsmith. 
 I also have a Rega p6 that has a new Exact cart that I believe is like double the output of the Soundsmith. 
 But I hate that Rega table and sound.
 The only way to try is swapping out the cartridges. 
I guess I should suck it up and hook up the nasty Rega and see what it does.

I agree the Schiit Loki will solve your issue. Its truly a quality piece of equipment. I have one and used it when needed, after moving on to a Luxman 590 AXII I no longer have a need for it.

"My god man, get a Schiit Loki!!!"

I'm also looking for a similar solution as the OP and am wondering how would the 20Hz control on the Loki blend with speakers that only go down to 35-40Hz? My concern is getting a "single-note" bass unless they have implemented a nice slope which could help with the transition to higher frequencies. Any input from folks using the 20Hz control for boosting the bass would be helpful.  

Yes, the Loki would work. You would have to adjust it for every different volume so it would be cumbersome. You could also not construct accurate opposing filters to your hearing ( Fletcher- Munson Curves.) Not enough bands. The best solution is a continuous band digital equalizer programmed to follow the Fletcher Munson corrections with volume change. To my knowledge there is no equipment designed to do this at this time. The Tact 2.2X and the last TCS are the only units I know of that had this capability. Anthem and Trinnov should get on the ball. 20 years later and nobody has yet to match Radomir Bozevic's technology. Dynamic Loudness Compensation is a gas. No matter what volume you choose the music sounds exactly the same. It is all done in the digital domain at 192/48. There is no distortion, none. Analog is wonderful as long as you keep to the "strait wire with gain" principle. Every time you do something to the signal you add distortion. Not so in digital. You are just juggling numbers.