The Q300 can stand up to amps which are many times its price, if matched correctly. And I think that they match well with the A19.
I'm not an Arcam fan, I should say - I know WHF loved the amp and I'm not saying it isn't a bargain. But the business about being careful with partnering equipment is a red flag.
I would not spend £600 on an amp. For me, you get so much more if you stretch to a Kandy or the new Nait 5is - and you don't lose that much if you save the cash and go for something from NAD or Rega a little lower down (or, if you don't have a DAC already, the NAD 356Bee, at almost the same price, is a far better choice - the amp may - MAY - be a step behind, but it includes a decent DAC, which if you don't have one already, will most likely improve your sound noticeably irrespective of the amp).
I feel like the Arcam is a bit bland - not so different from a home cinema amp (except with less power, and lots of money spent on the fancy metal case and the headphone amp, which are wasted unless that's a big priority for you). I'm not great fan of the Cyrus 6a either, but at least you would never call it bland.
It's a tough price point. Look how few amps at that price get five stars from WHF. And I would argue the ones that do don't deserve them - they either have a very specific sound or 'need very specific partnering equipement' and that sort of reviewing gymnastics.