JRDG Concerto has been replaced by the Continuum 250 and 500 integrated amps that have just started shipping.. They use the much newer circuit of the Capri for preamplification. The 500W model also contains the same Power Factor Correction (PFC) circuit of the JRDG 312. I Have not heard the Continuum yet, but it/they may be worth exploring if you enjoyed the Concerto. PFC can be applied externally to the 250 model through the new JRDG PC1 conditioner/rectifier unit.