Esoteric K-03 or K-01

Mike60, thank you. Yes K-01 is great What is great about it to me, that it is a great cd transport, great DAC and (in my system) I use K-01 to drive amp direct with great results. It is a keeper for me this time for sure.

Denon1,
It sounds very much like you are having a great time with the K-01.
And you are also happy driving your power amps directly. Your amps and speakers clearly are all singing together in synergy with the K-01.
I am curious as to what filter settings you have settled into.

Jon2020, as for today my K-01 has about 300 hours on it and all that time I use 4 upslamping and SDLY1 filter. To me this combo sounds most dynamic and airy. But next step I will try is to burn 2x with FIR1 filter becuae this combo has a potential to sound great also.

Hi Denon1, after break-in of Slow Delay 1 and 2, I found 4X with SLow Delay 2 to be more harmonically interesting and open sounding than Slow Delay 1. Slow Delay 1 seemed instead more tube-like, and a little limited in bandwidth. G. with Slow Delay 2 to have

JON202, I think the Vienna music arequite efficient speakers and that the reason (yours and partially mine) that you have to set volume control almost to the max on your K-01 because Bryston has low input impendence and K-01 does not have enough juice to drive Bryston direct. My krell has much higher input impendence, but still I feel that I have to compensate with much higher volume setting to get better dynamics, bass and soundstage.
And you know that both Bryston and Krell are great with dynamics and bass.
So I think I have to agree with Guido advice and we have to get active pre-amp to get full potential from our gear. It will come with the price so.