In Copenhagen, just across The Bridge from me, lives slowdiyer. He has designed the Muffsy Clone, his own version of the Muffsy that suits his needs exactly.
It is a mono version with single instead of dual op amps, which lets you use op amps like LME49710, LT1063, LT1028, AD797, OPA627 and more. Being mono, you can use two power supplies and run it as dual mono if you'd like.
It does away with the variable input impedance, retains the variable gain and adds a mute circuit. The Muffsy Clone has space for a really large output capacitor as you can see in the picture below.
The form factor is 100x37 mm, compared to Muffsy's 84x56 mm. The boards are designed to be stackable.
There are a lot of other considerations that he's taken care of, all of which are described here. The same blog post also includes all of the project files, enabling you to make one for yourself.
I'm anxiously awaiting his listening experience, as he's yet to finish the power supply to fire it up.