Upgrade from Pass Labs XA30.8 to X250.8. Worth it?


I am getting ready to make some upgrades to the system. I currently running a DAC into a BAT51SE, then a Pass Labs XA30.8, then finally into Decware DM947 speakers (don't worry if you've never heard of them; not the last word in speakers, but have been doing a solid job for about 5 years now.)

I am contemplating moving up the Pass Labs amplifier line, and the X250.8 looks attractive. I would like to hear more bass authority and definition, but I don't really want to sacrifice the mids and highs of the 30.8. 

I would love to hear some of your impressions of the X250.8, especially if you are able to make some direct comparisons to the XA30.8. I've spoken with both Mark at Reno Hifi, and Kent English of Pass Labs; both are wonderful and informative people. What I am interested in now is the opinions and experiences of end users of either of these amps. 

Thanks! 
willrich47
there are many Pass dealers that do not use power conditioners, so be careful  before you buy...
I've tried several conditioners on my amplifiers and always preferred them without.  I use dedicated 20A circuits to my JC1's.
Our Sound Application RLS power conditioner feeds our front end components (Meridian 800, 861v8, 621, Oppo 205) via CH Acoustic X20 power cords. This creates a very noticeable improvement.
Our Pass amplifiers are plugged directly into dedicated 20 amp circuits with CH Acoustic X20 power cords. Plugging our Pass amplifiers into our power conditioner has the least improvement and we leave them plugged into their own dedicated 20 amp circuit. This, I believe is because the Pass amplifiers have a very well regulated & filtered power supply,

I thought I would follow up to give some closure to anyone reading this down the line. I always like to hear how people’s decisions turned out. Hopefully you do too. 

 

I purchased the Tekton Double Impacts, largely due to the advice I got from members here. While I am not ruling out an amplifier upgrade at some point in the future, I think the Double Impacts have had a more significant impact on my system, than an amp upgrade would have. 

 

The Tekton Double Impacts: 

 

The DI’s need some time to break-in. When I actually got my pair, I was surprised to hear they sounded “OK.” And by “OK,” I mean thoroughly OK, middle of the road, mediocre, and most of all: disappointing. But, it didn’t take long for the midrange to start opening up. The mid and upper range only took about 3-4 days to open up and sound wonderful. The bass, was a little different. 

 

I’ve been using an SVS SB16 subwoofer for a little over a year. When I started using the Tekton’s, it seemed apparent to me that the sound was improved with the SVS. A little over 30 days after getting my Tektons set-up, the bass seemed to change. All of a sudden, there was too much bass. I turned my sub down. A couple of days later, it seemed like too much again. This time I turned the subwoofer off. I eventually achieved the best integration with the SVS by crossing over at around 35-40 Hz. My RTA app on my phone says I had a relatively flat response down to 20 Hz. 

 

I remembered an email conversation I had with Victor Khomenko a while back. The VK-51se has two sets of balanced outputs on the back. I had asked VK if they could both be used at the same time. He said they could, but I had to be aware of the combined impedance of all the amplifiers attached to the VK-51se. 

 

My Pass Labs XA30.8 is relatively easy for my preamp to drive. The balanced input impedance is 100K Ohm. The SVS SB-16 on the other hand, is not as friendly; its balanced input impedance is 22K Ohm. I believe the combined impedance is found through the calculation (100 X 22)/(100 + 22) = 18K Ohm (I would appreciate if someone with some actual EE knowhow would fact-check me here).

 

As an experiment, I removed my SVS SB16 subwoofer from the system entirely. In my system, the DI’s start rolling off at about 40 Hz, so I lost some bass extension from the removal of the SVS. But what I gained was more drive and authority from the DI’s, and more color and clarity through the entire range. 

 

I don’t believe that I noticed this with my old speakers because they simply lacked the clarity of the DI’s, and did not have the same bass extension. With the old-speakers, the SVS simply improved the overall quality of the system. With the DI’s, there is a clear trade-off. Bass extension for overall sound quality (especially bass quality).

 

I have had my SVS completely unhooked from the system for about 2 weeks now. After about 1 week, I added it back to the system and found I disliked how simply hooking it up to the preamp affected the system. I quickly removed it from the system again. This has been an unanticipated side effect of adding the DI’s to the system, and has all but de-railed my plans for a second SVS-SB16 subwoofer. 

 

If anyone has some clever tricks for getting around this problem, I am all ears! 


@bobheinatz I think you were right ;-)


Just for clarity, the SVS SB-16 subwoofer is still the single best sub I've heard. I simply think the impedance drop is having a negative impact on the sound of the overall system. If I could use it without changing the load on the preamp so much, I think I would have some stunning results.