Based on Zero Fidelity's & Steve Guttenberg's reviews I pulled the trigger on the Spark.
Man she is nice but yes speaker matching is required.
On my Klipsch RP-600M's it does very nicely indeed and well into hard rocking level dB's.
On the KEF LS50's not so much. lower listening levels (for me;75-80dB) do sound noticeably better than the 600M's but when a head nodding song comes up, cranking it up doesn't come out so well. The LS50's are just a bit too hard to drive. Fair enough though, it's 20w.
In my current circumstances I can only choose between 130wpc from an Onkyo receiver or 20wpc from the spark.
The Spark's sound quality is so far above the Onkyo I've packed the KEF's away in favour of the enjoyment the Spark's sound quality gives even with the lower SQ 600M's
Granted there are far better choices than an Onkyo receiver but for many the spark is their first dabble into audiophile SQ as it is for me.
OMG what a beautiful introduction for such a reasonable price.
Pretty sure this introduction will now have me broke for the rest of my working life... broke and happy tho!