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
Well, for anyone interested. I finally got in a XL-600 amp to compare to the 9505 Model. The XL-600 is Much better. Richer, Fuller sound. As well as the bass being much tighter. The 9505 just couldn't handle the Polk Audio Rti-A9 speakers that are rated at 250 watts a channel and 500 peak. After listening to 2 songs with the XL-600 my girlfried says wow that sounds a lot better. She knows very little about audio and didn't even know what I was hooking up. I was going to bi-amp the Polks but I don't feel I even need to now. Amazing the amp was made about 25 years ago now.
Hi Sundriednm

Was the XL-600 fully stock or was it modified? From what I've read the Hafler 9505 was supposed to be one heck of an amp. Let us know your thoughts after you spend more time listening to both amps.
The XL-600 is stock. Did some more listening. The XL-600 has a great sound stage and imaging. Better than the 9505 in my opinion. BUT, after listening for a couple days, the XL-600 was very tiring on the ears. Lot of fatigue. That doesn't happen with the 9505. So I bi-amped them with the 9505 on the high end and the XL-600 on the woofers. Sounds excellent. Amazing and not tiring. The speakers were meant to be bi-amped. Sum it up. NO way the 9505 has the power to push the Rti A9's. Bass was very very loose with the 9505 alone. I thought it was the speakers. It was the amp.
It is my opinion that the XL600 and the 9505 do have similar sounds. Only got to audition the 9505 one time though and it was not on long enough to really get warmed up. I own two DH220's, one DH200, one XL600 and a Pro5000 and a DH110 preamp. Been buying defective units and fixing them in my retirement. Just recently got the XL600 and it does sound nice and smooth, IMO. However, strangely I find that the Pro5000 seems to have the most clarity of them all. A good recording on the 5000 sounds like it is taking place right in the room.
Well, my XL-600 is having problems in one channel now, so I will be taking it to a repair shop. Maybe I will buy an upgrade kit for it as well. Hopefully, the Amp sounds more like the 9505 then?? Thanks for your feedback.
I have never heard a Pro5000 before. I will check out prices on that.
Thanks