Integrated Amplifiers

Dubbed a ‘Personal Audio Integrated Amplifier’, and rated by Rotel at just 25W/8ohm, the diminutive DX-5 is, in practice, no shrinking violet. In reality it will deliver 2x33W/8ohm and 2x46W/4ohm with sufficient in reserve to support 52W, 90W, 137W and 156W into 8, 4, 2 and 1ohm loads, respectively, under dynamic conditions [see Graph 1], below. So the DX-5 will drive speakers well beyond its notional pay grade with greater ease, and perceived loudness, than that 25W specification might suggest. Rotel also claims an uncommonly flat ±0.17dB response from 10Hz-100kHz which, in fact, it meets and holds to within ±0.15dB into any load from 8ohm down to 1ohm. The A-wtd S/N is a little below par at 78dB (re. 0dBW) but distortion is, again, rather better managed than Rotel’s vague ‘<0.03%’ rating indicates, holding to <0.01% over its rated 1-25W/8ohm at 1kHz and falling to a minimum of 0.004% at 3-5W. Versus frequency, distortion increases slightly at the extremes – 0.013%/20Hz and 0.031%/20kHz (all re. 10W/8ohm) – but this is to be expected.

Testing the digital stage via the speaker outs (2.18V into 47kohm re. 0dBFs) the A-wtd S/N is an improved 90dB and THD a moderate 0.018-0.039% [see Graph 2], dropping still further to 0.0018-0.014% over the top 20dB of its dynamic range (all re. 20Hz-20kHz). Low-level linearity holds true to within ±0.5dB over a 100dB range while jitter is suppressed to 85psec over all sample rates with 24-bit data. Incidentally, the coax input only accepts 44.1/48kHz data. The ±0.1dB response (20Hz-20kHz), and 74dB stopband rejection, are entirely determined by Rotel’s choice of minimum phase filter from the ES9039Q2M DAC – the same filter utilised in the Michi Q5 CD player [HFN Apr ’25]. PM