Does anyone care to ask an amplifier designer a technical question? My door is open.

@bdp24 That's actually a good suggestion, and easy for me to do, and I have no good reason why I haven’t. I had a Forte model 4a for awhile as well (50 w class A), but never tried that on Maggies either. I have different systems in different areas of the house, and typically don’t mix them (?). I did try a passive preamp in the main system recently and did Not like how it made the system sound. Maybe my preamp isn’t too bad after all... I will try the Dynaco with the Maggies this weekend. Thank you for taking an interest in my quest for sonic nirvana! Lol

@kellydreams   . I did try a passive preamp in the main system recently and did Not like how it made the system sound

Not knowing the passive and what is was driving, including cables I would say this: 

I have no problems with passives. If one thinks of it as the volume control on an integrated that is somewhat separated physically the question becomes: What is in the way? What might be loading the passive? Generally the problem is cable capacitance or output/input impedance problems  (I wont say mismatch). 

Heres the way I look at it. In an RM-10 the input is right to the grid of the tube. In a preamp its the same thing. Why should it sound any different?

People do like preamps for other reasons, many of which may be imaginary. I made lots of preamps. Of course you need one for phono.

Bill Johnson told me they sell twice as many preamps as power amps. Seems people like to play with preamps more. Some say because its the thing you touch. 

In my system i got tired of the cables from the pre to the crossover. I wanted something really simple.

Because the RM-3 crossover has two knobs for high and low output I decided I needed only one, the bass and so made the treb pot into a volume control. Reduces cables and connector problems.

Now I think the way to make a crossover is with several line inputs, volume and bass level. So simple. I adjust the volume and sub level (100 Hz and down) on most every CD.

If you care to share the specs on the passive, cables and power amp we might figure out what was happening?

Roger - What brand and model subwoofer do you use ?

For full range speakers in particular, aren’t speaker efficiency ratings only useful for determining power needed if they cover the lower frequencies, which is by far where the most power is needed to deliver flat frequency response and avoid clipping?

Don’t power requirements for flat frequency response increase exponentially with lower frequency?

Also FWIW it has been bandied about that manufacturer published speaker efficiency ratings are often let’s just say not completely accurate. True?

Also for that matter do some otherwise highly regarded amps cheat by not even attempting to deliver flat frequency response down to the traditional benchmark low frequency limit for hifi, ~ 20 hz or so?

@ramtubes. 

I’m not ready to abandon passives from one less than favorable experience. The passive I have is a Luminous Audio Axiom... one input, one output, and volume pot. I listen to vinyl 95% of the time, so I was feeding it from the output of a phono preamp. To my surprise, the output with the pot at about the 10:00 position was approximately the same level as my tubed linestage at 9:00. The sound was bright.. too bright, and the deeper bass sounded more prodigious, but a layer of midbass was missing, and female vocals, which had sounded natural minutes before (through the preamp) were almost painful to my ears. It was like someone made the old eq smiley face curve on my system. The cables I’m using are old Tara labs solid core... 1/2 m from the ‘table to the phono pre, and 1 m from the phono pre to the amplifier. The amp sensitivity is rated at 900 mv, the cartridge has an output of 2.5 mv, and the phono stage is 42 dB/47k. I was going to question you about preamps, but didn’t want to stray too far from the thread topic. However, as I have found, others may be interested in your answers. I read forum threads that interest me frequently, but rarely write in. This one caught my attention more than usual because it was started by someone who actually builds this stuff... and is known to do it successfully. No offense to anyone else! I read all opinions and add them to my mental database. One thing I’ve learned is, what appears to make sense on paper is not always the case in practice. Thank you for your time. Truly