I tested the Havana, the Rega, the Calyx, the M2Tech Young and, a DIY 1541 based dac and the Neko D100.
The Havana had a nice timbre with acoustic music but too 'closed' on the top end.
The Rega was harsh, same with the 1541.
The Calyx was very good but a bit too laid back and I preferred the Young, especially with the additional battery power supply.
Finally a few months ago I've listened to the Neko and was love! Great dynamics, not as fast as the young, but with a natual decay of the notrs.
Fantastic timbre accuracy with acoustic music and small combo. I'm using it with a M2tech EVO with battery supply. I think the Neko and the Lambda are a very good match.
Many thanks for the response, i just bought a used Wyred4 sound Dac 2 from another head-fier , and I'm on the loaner list for the Neko , waiting for my turn . Hopefully one or the other is better than the Bifrost :)