Hi everybody,

I am new to rack mounting and have a few questions about heat management.
I currently use a focusrite 18i8 3rd gen. I'll soon buy an octamic ii (8 external preamps via ADAT) and presonus HP60 (6 channel headphone amplifier). I'm also interested in replacing my 18i8 with a UCX II in a year or so. My dream configuration will be those 3 units rackmounted in a proper flight case so I gain space in my home studio but also have the ability to easily take those units outside of my homestudio and be able record demos with my bands.
I am currently reading the manuals of both of these units and stumbled upon this (for the octamic ii and UCX ii): "When mounting in a rack, leave some space between this device and others for ventilation". I couldn't find any information on HP60 needs in terms of ventilation...

What's the best solution?
- Getting a 6U flight case (quite heavy and not easily transportable) so that every unit has a 1U space between each other? Maybe that's overkill...
- Getting a 4U flight case (more reasonnable) so that every unit has some space between each other. That solution has been explained in this topic: https://www.forum.rme-audio.de/viewtopic.php?id=25118
- Getting a 3U flight case (really light and practical), assuming that mounting the UCX II with the RME 19'' rackmount kit (https://www.thomann.de/be/rme_rm19_ii_rackmount_kit.htm) will provide enough ventilation to the unit and that the octamic II should be fine.

Thanks in advance for your insights and have a nice day