If HA-6A and HA-300 MKII were amps you would argue for, HA-2A is the one that’s impossible to argue against. Building on HA-3A’s success, Cayin Audio again wrapped a single-ended Class A NOS tube amplifier into a compact A4 size for the desktop … but reduced size, weight and cost at the same time!
HA-2A does that, but it’s no OTL pussycat despite its reduced size and weight. More than anything, Cayin’s baby of the bunch brings the benefits of output transformers designed and built in-house to meet the power requirement demands of modern headphones – both planar-magnetic and dynamic, high or low impedance.
Flexibility might be the first topic discussed with the lightweight and compact HA-2A, but compromise in quality was never an option. Cayin’s point-to-point wiring is de facto again for signal integrity, and HA-2A’s EI core output transformers surpass even HA-3A’s, extending signal out to 50Khz.
That frequency extension up high will already yield great improvements in HA-2A’s mid-range and treble compared to HA-3A, with Cayin’s latest preserving phase response in the human hearing range that much better for superior sound-staging, dynamics and imaging precision.
Mixing fidelity that was once the domain of Output Transformer-Less (OTL) amplifiers in this footprint with actual power – all while reducing in price – is a true feat of Cayin.
The sense of value doesn’t stop there, with premium New-Old Stock (NOS) valves – US-production Amperex ECF-82/6U8 driver and 17BF11 power tubes from the 1950s – included.
Operating the ECF-82/6U8 only as a triode unlocks load line and soft-clipping functions at the drawing board. Their presence at the voltage gain stage is significant, where the majority of an amplifier’s final sound signature is defined.
HA-2A’s novel implementation of the composite designs of both these driver and power tube types make for very interesting transfer characteristics and distortion curves.
Still, linearity is a given through the holy grail of bias operation, even at this price point, while tube voltages allow for large operating points. Measured distortion is below even the threshold of HA-2A’s bigger HA-6A and HA-300 MKII brothers.