help on changing capacitors

The key to changing out the capacitors is size.  Some caps are just to large to fit in tight spaces so be careful.  Increasing the numeric values for Power Supply capacitors will in general produces better bass so if you can fit them in, my recommendation is to do so.

I recently used the Milflex copper caps with very good results in sound reproduction - did not find them bright either.

Happy Listening.

Those look to me to be alum foil paper in oil.... I believe the miflex referenced above would be slightly better Paper in oil. Jensen still makes a copper foil, but I’m not sure its available in 1mic and I don’t think that they are paper in oil.... Either way, in general, I would prefer the copper foils. A good polystyrene would be excellent, but most likely just a hint cooler or less warm than a paper in oil. They should however be slightly more defined  Good Luck

Vcap Odams are a better choice for both sound quality and fit.  I directly compared to Miflex in both dac and preamp builds/upgrades and the Odam is clearly the better sounding cap. The Miflex sounds forward and a tad forced in the upper mids and highs compared to the Odams.  The Odams just deliver better better top to bottom coherence while also sounding more real and natural.  They are much smaller and will fit far easier making the job more enjoyable and neat. 

PartsConnexion in Canada also regularly stocks them

The ODAMs are 3 times the price. The OP had concerns over pricing otherwise I could have recommended CuTF at $1200 a set!