Ossidian

I only use 15" woofers. Adding a second 15” Hawthorne Audio Augie up top to increase bass response, dynamics and to load the room top to bottom. This really makes for a big improvement.

Could not disagree more. My OB speakers completely disappear and there is no hole in center stage. Everyone has opinions and my 40 years of owning 100's of speakers and owning a High End store for 25 years tells me different. You are entitled to your opinions but they are not necessarily facts. After seeing your system setup tells me everything I need to know about your opinions lol.

On my OB Hawthorne Audio Rainier MK III I find 2" toe works well.

Good article on speaker basis some may find interesting. Speaker Off Axis

Lol. The amp is on 2" acrylic with 2" footers. The DAC is under 3" footers. The class D amps do not give off any heat on the bottom. Appreciate it though.

McIntosh MC2000 tube amp direct to McIntosh MDA1000 DAC. This is the way I like to hear my tube amp mostly.

What I would have given to have met Saul Marantz. What a legend Saul is. I still have my 10B tube tuner.

Yes, but it is $500 and you are right it is still a good value. Old stock A-9010 represent a great value.

Looks like the tech installed some nice Russian and Hovland caps in your AP-900. It's amazing how swapping tubes affect the sonics. The AP-900 is quite a nice unit indeed.

True, if you are bypassing the preamp section of your integrated the Mapletree preamp tubes would be best to concentrate on. Without seeing the schematics on the Ap-900 I have no idea what role the 6N1P play in the integrated. I have searched the internet but found no information on the AP-900.

If you are using stock Chinese 6N1P the JSC VOSKHOD 6N1P-EB are nice upgrade and affordable. https://www.thetubestore.com/russian-6n1p https://www.partsconnexion.com/NOS-79469.html

Many feel that most of the better dealers or manufacturers will burn in tubes, not just for sound but for characteristics of matching or failure. https://www.diyaudio.com/forums/tubes-valves/195141-burned-power-tubes.html

Current 12AX7 Tubes Comparisons

You are spot on, the manufactures of "some" amplifiers goose the bias to bring up the power stated or advertised but may not result in a pleasing sound to the customer. I also refer to the Jones table as well, good information. Personally I feel after looking up your AP-900 (if I am correct) that you may benefit more with changing the 4 x 6N1 and 2 x 12AX7 if you already haven't. NOS are great and even current GL 12AX7 would really help in the holographic imaging of the amp as the GL 12AX7 excel in that department with many pieces I put them in over the last 5 years. http://www.tedweber.com/webervst/tubes1/calcbias.htm

The bias setting is generally determined by the designer / builder and listed in the owners manual of the amplifier in question. "Generally" tubes biased hot equates to stronger overall output, more bottom end but at the expensive of clean headroom and early breakup. Biasing cold the amp can become thin sounding, anemic with bass sounding a little weak but with cleaner headroom with later breakup. I like to find a place in the middle that my ears enjoy and as a rule I never go above the recommended high bias setting without first talking to the engineer of the product or at least an engineer from the company of said amp. Interesting Info On Vacuum Tube Bias

Absolutely. David Chesky (Chesky Records), Mark Waldrep (AIX Records), Professor Keith Johnson (Reference Recordings), Kevin Grey and I can go on have gone on the record (no pun intended) as mastering is the most important process of the "final product". Proper mic technique and the whole recording process is also very instrumental in creating a great product. If the recording is not well recorded or mastered the "numbers" like 24/192 will not change anything nor will putting it into a larger bit bucket from my experience and many others. You simply cannot polish a turd.

Specs are not representative of sound quality. Another myth is good "specs" equates to good sound. About 30 years ago, Dr. Hirata published a paper that showed the differences between a number of discrete amplifier designs, both tube and transistor. It made a difference in these cases. As I recall, the best amp was the Marantz tube 8B, and the worst amp measured was the Crown DC-300. Why? That is the question. It was certainly different than harmonic distortion tests made with the same components, that tended to predict the opposite result. This is WHY we like to note and even develop tests that show SOMETHING not seen by harmonic distortion measurements and its relatives. In solid state nulling the 7th and 9th harmonics are crucial to take the edge off the sound as presented in the old HP book from the 30's. This has been discussed with myself, Scott Franklin, Bruce Moore and John Curl on more than one occasion. Though I admit I have not tested 40 years worth of amplifiers. https://linearaudio.nl/sites/linearaudio.net/files/Hirata test engineering report 1981.pdf https://www.cnet.com/news/can-sound-quality-be-measured/

Care to explain your insightful reply?

His system may be extracting a little more from the recording but as nitrofan stated your system is most likely more faithful to the recording. Personally I find 16/44 are great if well mastered, the mastering is more important than numbers in my experience. But a good system can reveal weakness in poor quality 320 mbps and under.

I understand you are not looking into tubes at the moment but you may wish to look at some options around $2200. http://shop.grantfidelity.com/Consonance-Cyber100-15-Year-Anniversary-KT88-KT120-KT150-integrated-Tube-Amplifier.html http://shop.grantfidelity.com/Consonance-Ref-5-5-MKII-SET-Integrated-300B-Tube-Amplifier.html

The Onkyo A-9010 integrated is a great bargain for someone looking for a good taste of Hi-Fi on a budget of $300. https://www.cnet.com/news/low-costhigh-performance-contender-onkyo-a-9010-integrated-amplifier/

I find the Genalex GL to have superior extension and a taut bottom end. I also find the Genalex to have a bit more midrange extension albeit a little forward. Have had JJ and prefer Genalex Gold Lions hands down.

The question you need to ask is the CD you have mastered from the original master tapes. If the answer is yes it its doubtful playing the DSD download mastered by Kevin Grey from the original master tape that has been put into a bigger bit bucket will offer more than the CD from the master source.

Red is bad and green is good. Red means there is very little dynamic range, very little loud and low passages. Most of todays CDs are loud all the time sadly enough. Beware a lot of remasters from the big labels are terrible with respects to dynamic range. I find a lot of the older Cds from the 80's and 90's to sound well. At the end of the day the mastering is very important, you cannot polish a turd.

My take is tubes sound best when new and only further degrade over time until they need to be replaced. My experience is if you do not care for the sound of the tube additional time will not make a significant change in the tubes sonic signature. I do however believe ones ears and brain may need to become accustomed to the sound.