I didn't have a chance to listen to the Mytek, Benchmark or Lavry but as they are considered as studio/neutral dacs so I could help you partially. Since I had opportunity to hear some converters in studios like RME FF, Esi Juli@, both on speaker and headphone set ups, I can tell you that they share similarities in terms of flat response, they don't mask anything and can sound a bit harsh and dry when they are feed that way. I don't think that they are not too much different in that regard since they are oriented to the same market. It is more difference in terms of features and driver stability which are well regarded in that field.
I'm using Hegel HD11 (over coax) and it does sound different to my ears. It's not flat, by any means. Hegel has boosted bass but in very controlled way. It is boosted in whole range, so it is not just a spike, but it is fast detailed and it's only there when it's called for. Because of slight elevation in low freq, mids e.g. voices can sound a bit throuty or up front (I played with parametric eq, where I tried to lower bass response and detect bass bleed into mids but there wasn't any, which is odd). Upper mids where normal, with right amount of body and piano was sounding unbelievable real with subtle dynamics while retaining the body (on good recordings). High freq are very interesting since Hegel is walking right on the edge of neutral and warm (cut off). I can say this are the best high freq that I've heard to date and I dare to say most neutral. I am using LPG100 which has near 2W and with xlr connection, foobar on pause, I can not detect even a slightest hum in background over 3/4 of the dial, which relates in impressive soundstage, layering and imaging. At the end, this dac is so elegantly balanced that even with elevated bass and lower mids freq, upper mids with body to it (this is very problematic spot as you all ready know), high freq that are never bright but far from rolled off, I can not detect any spikes (without using sine sweep, just music) to the point that it almost feels like dead neutral.
I know you are eying HD20 which based on things I've read can be only better.
my 2 cents
Cheers
