Compared with buying a newer streamer/DAC-preamp at this money, £2,500 is a touch strong rather than an obvious bargain. Your eight comparable listings put the median at £2,013 and the 75th percentile at £2,425, so this sits above the normal asking range; I’d want the later /3 Katalyst version, excellent condition, and complete accessories to justify it.
The Akurate DSM remains a serious all-in-one: an accomplished network player, DAC and preamp with substantial connectivity, good analogue performance, Space Optimisation, and Linn’s generally strong long-term support. It can simplify a system considerably, especially if you value HDMI, phono, or Linn/Exakt integration. With the version unspecified and condition unknown, check the exact hardware revision, display and streaming operation, remote, packaging, and service history. At £2,500, negotiate toward £2,100–£2,300 unless it is a particularly clean /3 example.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.