fdd5d689_e_Notes_on_Coupling_Capacitors__Impressions_HV
[Brand] Solen bypassed with 0.1uF Vitamin Q $2.65 + about $1 on ebay [Impressions LV] The note here is that this made a world of difference. Bypassing causes its own phase distortions apart from the ones caused by the low pass filter, and whether bypassing is a good idea in a particular circuit depends whether the good done by the bypass cap outweights this harm. In the case of Solens, bypassing can offer a huge improvement. The Vitamin Q cap here added some midrange lushness, a ton of top end detail, and did almost no harm. [Rating] 2 ½, 3 [Impressions HV] 
Again, a huge improvement. Most the harshness of the Solen's is more or less gone with an added midrange clarity and richness. Still not as nice as the Auricaps, but the price is about a fifth as much. Indeed, if I were building a system on a tight budget, this is what I would probably use.
ecp audio diy: Some Notes on Coupling Capacitors
Impressions HV