[admiralnorman]

One longtime standby is the Sony MDR-7506. Foldable, closed-back, very portable. A little clampy on my head, though probably good for smaller ones. However, the cable is coiled (like an old landline telephone) and hardwired, not detachable, if that's a consideration.

This, plus pad swap.

 

[Coolmoose]

I'd take a look at the ATH-WP900, small, easy to carry, looks and sounds good. They are also within your price range.

 

[lightflower]

Either the 770 pro or akg 361/371 models. Not many good cheap closed backs to pick from.

 

[Ioanast]

AKG 371 from me too

 

[dstarr3]

AKG 275

 

[sinbarambam]

Thank you everyone for your recommendations. One of you suggested the audio technica ath m50x and this made me realise I own one of these. I use them occasionally for DJ-ing (they fold over-ear so are ideal for this) and had never thought of them for non-performance listening. On trying them out I realised they're actually really quite good for this. I swapped out the old pads and when paired with the Ifi Go Blu, the result is fabulous.
Plus they're incredibly sturdy. I must have dropped/ stood on them at least a dozen times over the years and they're not even scratched.

Happy camper here