Hafler XL600 Vs Hafler 9505 Much difference?


Hello all, I am new here and still learning to navigate the website. I have been out of audio for a number of years. I had an old Hafler XL600 years ago and really liked it for the price. I am thinking of getting into audio again and am considering purchasing either an XL600 or the newer Hafler 9505/9500. I have read there have been a lot of improvements in amplifiers in the last decade. Is that true? How much difference is there in the amps I am refering to? Would I notice a difference between the XL600 and the newer amp? I hope to purchase Boston Acoustics VS336 speakers to go with this.
Any info would be helpful.
Thanks
sundriednm
Chances are good that what you're hearing as a, "bass problem" with the 9505, is a case of expiring power supply filter caps. I've been using mine to power the bottom of my actively bi-amped system, for a number of years. My filter caps went south, about three years ago(symptoms appeared earlier, of course). The differences would be much more noticeable(across the board), if the amp was used full musical bandwidth. Especially given that you seem to enjoy cranking your tunes. These made a world of difference, but you have to leave the top off the amp, as they are slightly taller than stock: (http://www.digikey.com/product-detail/en/B41456B9229M/495-4228-ND/2269437)
Should have mentioned; those caps are slightly(10%) over the stock uF value, very low ESR and long life. You can further improve your 9505's presentation, with a pair of these(easy to install) FRED bridges: (http://datasheet.octopart.com/VBE17-06N07-IXYS-datasheet-143416.pdf), higher quality binding posts and RCA's, all of which can be gotten from Michael Percy: (http://www.percyaudio.com/Catalog.pdf)
Ok, assume I know nothing about audio, as that appears to be the case. :) What is a FRED bridge?
I'm guessing you didn't check out the link that I provided.
(F)ast (R)ecovery (E)pitaxial (D)iode It's been my
experience, that their being substituted for common bridge
rectifiers, eliminates much grain/noise from gain circuits,
resulting in a more natural presentation. Regarding the
leaving off of the amp's top: I suppose it could be dangerous,
if there are those around that might place their hands in the
amp. I'm not faced with that issue. If I were; I would use
stand-offs(about 1/2") and longer screws to reattach the top.