This type - K40Y-9 is the best for audio DIY projects.The capacitors are new and never used, NOS - new old stock. Taken from the military storehouse in excellent condition.
One of the best on Russian Audiophile market are PIO capacitors of type K40Y-9.
The conductor is made of aluminum foil and the dielectric is oil saturated paper, glass sealed in a metal body. These capacitors provide excellent sonic characteristics, high tolerance is kept within a wide temperature range