Opinions on ARC DS450?

Just wondering from those who either own or have auditioned the new ARC DS450 power amp how similar or different is the DS450's sonic signature to their tube amplifiers. Please comment if you have experience with their current tube power and/or mono block amps and the new DS450. Not looking for speculation but actual experience with both. If you own the DS450, please let us know what preamp and speakers they are matched up with. Thanks very much.