I suggest you take a look at Thomas Mayer's 10y Line Preamp.
His tube gear is hand built by him to custom order with numerous options available.
He is a very experienced world class engineer and designer. The parts and build quality are at the highest level. He is even producing his own tubes (Elrog brand). How many tube amp designer/builders are doing that?
You mentioned being in Asia and I believe he has a shop representing him in Hong Kong where you could audition his designs. It might also be possible in Singapore but maybe only Hong Kong.
You can email him to find out more. He answers promptly and deals personally with each customer. Very few (if any) others offer all that.