So having built alot of Kevin's boards, I can tell you that his 1uf cap of choice is the smaller wima at mouser. Most 1uf film caps won't fit there good because the other components are to close. I also wouldn't recommend an electrolytic cap in the audio path. If it were me I would use some 1uf mlcc caps there. Will fit and be more stable than an electrolytic. If you don't have any, shoot me a pm if your in the US and I'll mail you a couple.