What Tips would that be?
I've notice you also have the Acoustune HS1650CU, Any insight / comparison between the two?
I get the best seal and most pleasing sound from the Penta using the UE900 green core silicon tips. Size L. I have also used the Spiral Dots, size L. Sound is also very good but the UE fits my ears better. Both are shallow fit as they block my ear canal rather than insert into the canal.
I do like the IMR Zenith. It seems to have similar tonality, however the ceramic tweeter seems to bring out the treble minutiae better than the BA of the Penta. I haven't yet decided whether this is a good thing or not. I do like the larger more spacious sound with the vents open. The Penta cable is much nicer than the more springy Zenith cable. I have not tried any 3rd party cables with the Zenith as yet. Isolation and fit is much better with the Penta if that is a major consideration as the Zenith is quite a bit larger which might present an issue for those users with smaller ears. I do consider the Zenith to be a very good IEM especially for use in quieter environments if fit is not an issue.