Thanks for this good review. You have not cleared me up what are really the differences between the 500 and 650 model, but I feel that both are close each other.

@Karl2009 - To elaborate further between the 500 and 650.  The 500 has a bit more clarity and precision.  While the 650 has a slightly smoother overall sound signature, that in its own way is very pleasing to the ears.  I would suggest the 500 for more analytical listening, like for classical music and the 650 for main stream rock and pop.  Though both are versitle enough to jump around from genre to genre. 

Wow, this is both funny and informative Very good review. When you listen to them for prolonged time, what are the specific issues you encounter, since you write that the 650 are more for prolonged usage?

I understand that you are always talking of the v2 version.

thanks for the review, enjoyed reading through! and as always..stunning pics

@Mommerman, I would not say there is any issue, more of the fact that because of the detail the K's 500 grabs, compared to the slightly more relaxed playback of the TY Hi-Z 650, that the brain will be doing a lot of extra work over time grabbing all the extra information, while the 650 is no slowch, it does go a little easier on the ears.
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@Karl2009, yes this is the V2 of the K's 500.

I understand that you talk of v2 version.

Fighting words on the AliExpress product page, "Kill Monk Earbud". I should hope so – Monk is a $5 earbud! Unless they meant the Zen, then they need to change it. I wish you had a chance to compare with Venture Electronics Zen.

@rkw, I wish I had a Zen to compare it to as well. 

A great review, very comprehensive.

Great review. However, I do compare them with Zen 2.0 and Zen 2.0 has more bass to be honest. Still burning in my K500 though.
 
Btw do you use any foams with the K500?

I don't doubt the Zen 2.0 has bigger bass, I have heard that does do quite well down low.

For the K500, I have tried it with many types of foams, Normal, Donut and the thin VE versions.  All do change up the signature a tiny bit.  I like the thicker foams for comfort and the VE foams for the best quality listening.  

Do you have any suggestion about DIY this earbud for reducing microphonics? I thought if cotton wool or sponge is used to cover around cable hole, the microphonic may be disappeared. Does K500 excel Rose mojito + its stock HQ cable?

amazing review by my favourite earbud reviewer