Thinking of buying a solid state amp

Semi, if you seek a warmer sound, between the NiuForce and Bel canto Ref 1000 Mk.2, you may want to consider the latter. I have used both in my system driving Vienna Mahler speakers, and BC sounded a little warmer. . . NuForce may have been overdamping the bass among other things. I have reviewed BC Ref 1KMk.2 on Positive Feedback at:
http://www.positive-feedback.com/Issue43/bel_canto_ref1000.htm
My reference amplifier is the Rowland 312 which I adore, but it is significantly more expensive than the BC.
If you get any class D amps, be prepared to be very patient with break in. . . BC is relative benign at about 600 hours, NuForce seems to require about 1000 hours to settle down, and so do most Jeff Rowland amplifiers. BC is listenable out of the box, but NuForce and Rowland amps will sound pretty dry for the first couple hundred hours.

Semi, the Rowland 501 is a slightly older design. By itself it may be a little 'cool' sounding compared to BC Ref 1Kmk.2 monos. To perform at their best the 501 monos require a pair of the new Rowland PC-1 rectifiers. . . the sonic difference should be significant, but a pair of PC-1s also adds a non indifferent $3K to the cost of the 501 monos. BTW, never connect PC-1s to Bel canto or NuForce amps. . . you will blow the amps. PC-1 is to be used only with amps set to 240V operations, or amps that have universal autosense and autoranging switch mode power supplies. G.

Semi, none of the current class D amps that I have heard can be deemed slow, including the current breed of JRDG products. Nimbleness and authority on difficult speakers seems to be a common characteristic of class D amplification, as it is shared by all amps of this type I have heard: NuForce, Spectron, Bel Canto, Channel Island, Wired4Sound to name a few. The problem of early class D designs was rather a certain lack of harmonic development, only moderate microdynamics, and a slight dryness in the treble. The result was that early class D amps were not very involving and sounded 'matter of fact'. It was a matter of learning curve. . . Some manufacturers have addressed these issues by designing a variety of strategies, including various forms of pre power supply rectification: e.g. Bel Canto Ref 500 and Ref 1000 Mk.2 monos. I believe Spectron may be doing something like that in its designs as well. Rowland uses a rectification variant called Active Power Factor Correction (PFC) in some of its newest models. . . but the problem remained for his earlier designs like the 201 and 501 monos. . . so he created an external unit for performing PFC rectification for the 201 and 501. . . and that is the PC-1 device. Unless you want to go over the $10K mark, within class D amplifiers, you may have a look at one of the newest Spectron variants, BC Ref 1000 Mk.2, and Rowland 501 augmented by twin PC-1s. Above that price point there are at least the Spectron monoblocks and the Rowland 312--the latter being my reference amp. In the $30K+ range, class D amps to look at are at least the Rowland 301 monoblocks (configured for low impedance speakers), and the Levinson No. 54. Happy hunting! G.

GLI, what sonic differences did you perceive between JRDG 312 and Pass X350.5?

Thanks, Guido