I too considered these 2 integrateds a year ago and decided on the Krell Vanguard Digital. I had not heard either unit but I was still using the original Krell KAV 300i integrated, which is still going strong after 20 years of service (!) and I mostly loved it. I wanted digital inputs, thus I decided to upgrade to the new Krell.
I can say the new Krell sounds very similar to the original. It sounds nothing like some of the units which came in between, those with a softer, rounder, smoother sound. This one has the same powerful command, yet refinement (but not smoothness) of the original. It is not forward; it layers the soundstage back nicely and possesses a rich acoustic, full of color. But it is also robust and quite fulsome in the bass regions, perhaps a touch lose.
That being said, it is by far the most finicky, persnickety piece of audio equipment I've ever used - from power cords, to digital cables, to power conditioning and, most importantly to incoming digital data streams. This Krell tells you everything about the cables feeding it. In the most revealing way. And if it doesn't like something, it sounds like crap. I have had many enlightening experiments with power conditioners. The Krell is not fond of most of them. I have settled on an AudioPrism Foundation .05. Very minimal, clean, high current outlet power strip. The Krell seems happy.
However, I have had nothing but trouble with its digital inputs. Beginning with the Coax (RCA) out from DirecTV, it would not accept it. It crackles and pops and hisses. Switching to the Toslink and everything is fine. Suspecting a problem with the satellite receiver, I had DirecTV replace it with a new unit. Same result with the coaxial connection. The coax connection, however, works perfectly on my CD player.
Next I tried the HDMI input from my Cambridge Audio universal player. It was very inconsistent with this connection. Sometimes it would lock onto a PCM signal from a CD just fine. Other times it crackles and spit for few seconds before settling onto it. However, trying to get it to recognize a DSD datastream was almost impossible. Cracks and pops and then switching back to PCM. Occasionally it would suddenly lock onto the DSD stream, and it played beautifully! Gorgeous sound! But wen you stop the disc and press play again, it's right back to cracks and pops and spitting at me. Same with simply advancing track to track. Once you stop the player, the Krell had to reacquire the signal and has difficulty doing s every time.
These problems are not unique to this unit. I sent the first unit back to Krell and they sent me a different unit. Both units behaved identically. I feel this is a real problem with this integrated. I notice Krell is coming out with a new integrated this fall - the K300i (at $8,000 with the digital module). I presume Vanguard is being discontinued. I can't be the only customer upset with all these problems with it.
In the end, I like the sound. But these constant issues with the digital inputs make it most exasperating and frustrating to deal with. I'm ready to cut my losses and buy the newly upgraded Parasound HINT 6.
