Rekordbox 4.1.0 stop/start stuttering on playback within player

1) Operating System: OSX Yosemite 10.10.5
2) OS Type: 64bit
3) rekordbox version: 4.1.0
4) Using LINK: No 
5) Source Hard drive 
5b) Connection type: USB3.0 / USB2.0 / 
5c) Does the device have multiple partitions: No 
5e) With what utility did you format the device: OS X
6b) Connection type: USB3.0 / USB2.0 / USB 1.1 / FireWire / Thunderbolt / Network Share / Other (please specify)
8) Is rekordbox crashing at all: No 
8b) If not crashing, are there any error messages: No 
9) Are you able to repeat / reproduce the problem: Yes
9a) If yes, can you do it consistently: Yes
10) Does the problem occur with one specific song: No
11) Any other notes regarding your setup only:
12) Provide as much detail of the issue here:

Soundcard: Focusrite Pro 24

I have used Rekordbox with my Focusrite Pro 24 for months with no issues. I had to use a different sound card for a project but when i reconnected my Pro 24 Rekordbox now stops and starts playback every second or so stuttering on playback.

As soon as i disconnect the sound card it plays back fine. The sound card is relatively new and has no issues with it. Its strange how it worked fine for ages but now is having compatibility issues. Im not using any external devices, i only use rekordbox to organise my USB's which it does fine.

Any help would be appreciated.

Thanks