Hi Andrew,
Many thanks for the instructions above.

As it happens I had previously (some years ago) downloaded a version of Amplitube 3 from IK Multimedia as part of their 'Custom Shop' product - I just didn't realise it! The IK Multimedia website let me download it again from my user account area.

As you advised the download includes both a 32bit and a 64bit version so I was good to go and I have added the 64 bit version in BIAB as per your instructions (all seems good!).

Just for the record, I am not a guitarist (or certainly not an accomplished one!) and I never use Amplitube directly, but several of my favourite styles have 'effects' style guitar RealTracks that use the Amplitube plugin (presumably with presets that load with the style?) and I didn't want to lose access to them.

So far the 64 bit version of BIAB2021 seems a bit faster and a lot more stable than the 32bit version of BIAB2020. Not sure whether this is because I have moved up to 64 bit or whether 2021 is just generally faster and more stable than 2020 but I am happy to bank the win and move on!

Many thanks to all respondents for your support and suggestions!

Best Regards, Aubrey

If I hadn't seen such riches I could live with being poor.