The Boulder doesn't hold up in comparison to the Rowland Continuum 500, driving the same speakers. At RMAF, several of us heard the 2060 driving Vienna Acoustic Die Muzik speakers, pushed by a Boulder preamp and Boulder CDP. The Boulder had bloated bass that muddied the mids and left the highs dry and slightly acrid. The Rowland 312 was substituted and cleaned up the bass and added richness and detail to the mids and highs that was very apparent.
For grins, we then put the C-500 in the chain, fed directly by the Boulder CDP and it still maintained the bass control and interior richness.
In a separate room heard GamuT's large monoblocks driving their large, tower speakers. I preferred that sound to the Boulder driving Die Muziks, but since the system was completely different it hard to say, other than the GamuT is top tier and by no means behind Boulder.
I think this "tierage" concept is very flawed, but, if you're going to do it, then Rowland would not be a couple of tiers below the Boulder unit.
I disagree with Guido about the C500's break in time. It runs warm compared to most Class-D amps and seems fully broken in at around 200-hours.
For full disclosure, I DO own the C500, but most in the room for the Boulder/Rowland comparison owned neither.
You can fly to Soundings in Greenwood Village, CO and hear the Boulder and Rowland side-by-side for yourself. A Southwest Airlines, weekend fare ticket is a small price when considering an investment like this.
Dave