Amplifier brand/designer with the most unique and consistent “house sound?”

+1 on Ayre.  At audio shows, they are the rare solid-state company that always pleases my tube-lovin' ears.

John Curl Parasound gear. Anyone here have a rake on this?

Some one who has designed, built, helped design and build and passed his ideas on for others in the DIY field is Colin Wonfor, maybe best known for the Inca Tech Claymore and SECA amps. He also designed the original Tellurium Q cables, his latest work comes under the name of EWA Designs, but he has built some of the most extraordinary amps ever.

What is house sound?
I mean that a amplifier can be made much more linear and do not deviate as much from a flat line as a speaker does. That has more swing up and down from any kind of line.

I thinking if we want to deviate from a horizontal line with for example more bass and more highs so we get a smiley curve.

If a manufacturer consistent make amplifier that make a in this example a smiley curve.
Is that a definition that that manufacturer has that house sound i guess.

Or is the definition of a house sound something completely different?

The house sound is usually purposely implemented to avoid fatigue or harshness of the overall sound.. They look for a “pleasing” sonic signature for “most”.  Thats how PASS designs their equipment. It is a group effort and they ALL listen to and adjust accordingly.. 
Glad we have choices and various types of designers who give us the flavors we prefer.  I chose the Pass house sound overall mixed with a first watt amp which has its own secret sauce blended sound. the combination works for me. Just right of neutral leaning to warm.. 
also should be dependent on the type of music you mostly listen to.
No right or wrong when it comes to preferences.