I have spent. Lot of time with the xsp-1 preamp my brother bought it in June it has gotton better and better. In fact it was thin and grain the first 2 weeks once it got to over 150 hours it starting smoothing out .
Roughly 300 hours are needed to fully breakn this preamp
It may not be warm like a tube but the type of transistors and circuit
Give it. Big soundstage with nice balance. This is at least one professional
Review out there and their findings were very similar to my observations.
Also my brother leaves the unit on all the time to keep the circuit at optimum operating temperature, there is also owners manual on their site
And if you have any questions ,call their technical support they are allways
Available,emails are slow and sometimes emails get sent to the junk folder
Depending on your email setup,I saw a comment on no return emails
That could be why,just Call Them.p.s they give you a full month to
Audition the unit ,and with a 5 year transferrable warranty it is better then most even at several times it 's cost,and with free shipping a great deal and very versatile.try it yourself
I myself plan on buying one ,and spend the money on a Good power cord
Signal cables Silver Copper PC are excellent !!