Headphones

Limited specs for the HA 200 are provided, but do not include its power output. The short answer to this question is 1650mW/32ohm (single-ended) while the fuller answer, including how power is influenced by the HA 200's impedance settings, is provided in my boxout. Freq. response is also influenced by both the variable impedance of the attached headphone and the HA 200's output setting – its '8R' output giving the flattest result in the 'real world'. Into a uniform 32ohm load the analogue in/out response is flat to within ±0.01dB from 5Hz-20kHz, falling by merely –0.26dB/100kHz although the bandwidth and HF 'shape' is entirely influenced by the incoming sample rate and choice of filter when the HA 200 is utilised with digital sources.

Specifically, with 48kHz, 96kHz and 192kHz inputs, the response limits up to 20kHz, 45kHz and 90kHz are –0.2dB, –1.5dB and –4.0dB (FIR Long); –3.7dB, –2.9dB and –4.0dB (FIR Short); –2.3dB, –30dB and –7.7dB (Bezier/IIR); –4.6dB, –5.6dB and –7.7dB (Bezier); –3.6dB, –5.9dB and –13.2dB (NOS 1); and –3.3dB, –4.0dB and –5.9dB (NOS 2). The FIR filters offer the best alias rejection (102dB for FIR Long) but have the greatest time domain 'ringing'; the NOS options suffer no ringing but digital aliasing is suppressed only by the output analogue filter. If you are tempted by NOS filters, I would recommend 96kHz, 192kHz or DXD files rather than CD/48kHz. In keeping with T+A tradition, analogue in/out distortion is a very low 0.0002-0.0007% (20Hz-20kHz), increasing to merely 0.0009-0.0015% under load [see Graph 1] while residual noise is just –101dBV (8.9µV) – ideal for high sensitivity 'phones/buds. In digital mode, THD falls as low as 0.0003-0.001% (20Hz-20kHz) over the top 30dB of its dynamic range [Graph 2] and jitter is <20psec across all sample rates. PM