are all amps equal

First, get the amplifier/speaker match correct. The Usher BE-718 are not very
sensitive at 87db (actually measured 85db by John Atkinson in his Stereophile
measurements) , therefore they require a good amount of power. Although they
have a fairly flat impedance curve, their power requirements probably eliminate
most tube amps as the best match, including your ARC 150.2.

So, I would recommend buying a solid state amp (or chip/digital amp) with lots
of power (at least 200wpc into 8 ohms and 400 wpc into 4 ohms). Even 200wpc
isn't really quite enough power to give you realistic decibel levels on the BE-
718, but it will be a good start. If you can go to 400 wpc into 8 ohms, that's
even better.

Also, I would recommend buying a subwoofer since you're not planning to
replace the BE-718, which only go to 42Hz, and therefore are missing a
significant range of bass where much of the music lies.

03-28-09: Kijanki

Unless somebody listens to symphonic orchestra with big drums going down very low or needs special effects for the home theater than 42Hz should be fine (if its really 42Hz).

I cannot disagree more.

There is substantial bass information below 42Hz which is clearly audible (or discernible) in systems that reproduce it.

Piano goes to 28Hz, organ goes to 20Hz and double bassoon goes to 25Hz. This does not take into account bass from electronic music, nor does it take into account fundamental tones.

Anyone who listens to the same music on full range speakers versus semi-full range speakers will experience the difference.

If you're happy with bass that goes only to 42Hz, that's perfectly fine, but there's much more to be had.

03-28-09: Kijanki
Tvad - I understand, but shouldn't 42 Hz be fine if somebody listens to jazz or
popular music.

Not in my opinion, no. I am not one who is satisfied with the semi-full range
experience.

Again, all one has to do is listen to the jazz or popular music selection on a
system with full range speakers and a system with semi-full range speakers to
discern the difference.

Many listeners are satisfied with the semi-full range experience. For them, a
subwoofer is not necessary. Keslerd will have to determine if he wants a sub or
not.

no

03-28-09: Kijanki
Tvad - it's a trade off. I asked the question because I plan to upgrade my
speakers. Getting lower end (lower than necessary?)

Define necessary. My definition of necessary is 30Hz at minimum. Lower if
possible.

... will cut on definition, imaging etc (within the same
price range).

I cannot agree with this. Definition and imaging are not tied to price. In other
words, one need not spend a large sum to get full range bass, outstanding
definition and excellent imaging. I have heard Vandersteen 3A Reference
speakers which sell for about $1500 used. They have incredible definition and
imaging, and they go down to 20Hz. Von Schweikert VR4 Gen III HSE go down
to 16Hz, and sell for about $2500 used. They have stunningly good bass,
definition and imaging.

There are many other examples. You just have to do some homework.

03-28-09: Kijanki
...it seems to me that there is some correlation between quality of the speaker and its price tag.

Listening to just the two speakers I mentioned previously will prove otherwise.

I don't see how difference between 40 and 30Hz can change playback of bass guitar - I don't question it does, but just trying to understand it.
Kijanki (Threads | Answers)

IMO, you would be wise to listen to a wide array of full range speakers using familiar source material that you play on your less-than-full-range speakers, rather than basing your judgment on what you think you should hear based on your interpretation of frequency response charts.

The difference and benefit will be immediately evident.

03-28-09: Kijanki
As for the lack of correlation between price and quality - are you saying there is none and everything is just random?

I am saying price does not necessarily equal quality nor lack of quality.

Can one purchase $1k speaker as good as $50k speaker?

That example is a bit extreme, but I'd say one can purchase $3000-$4000 (retail) speakers that will outperform $10,000+ speakers depending on the brands/models being discussed.

If you're willing to buy used, then you can cut the cost in half.

There's plenty of expensive junk on the market, IMO.

I think you'll both agree that providing bass that is
simultaneously clean, undistorted, deep, and high in volume, requires big
drivers (at least 10-12 inches, or else equivalent multiple smaller drivers),
which means bigger cabinets, and both the larger drivers and the larger
cabinets tend to result in higher cost if quality is not sacrificed.

Regards,
-- Al
Almarg (Answers)

On absolute terms, yes.

However, much depends on how big the gnat's ass is that one wants to
examine.

If one's primary concern is lack of bass distortion, and one does not have the
room to accommodate speakers with large bass drivers, then definitely
choose semi-full range monitors and sacrifice the full musical experience.

If one's primary goal is the full musical experience, then one may have to
sacrifice a little in bass definition and clarity. But again, it's dependent on the
size of the gnat's ass one is examining.

I know where my preference lies. I'd rather enjoy the full musical experience
and sacrifice some clarity (but I don't think I sacrifice much clarity or
definition, so the point is moot for me).

The above mentioned speakers from Vandersteen, Von Schweikert, plus
Emerald Physics, Coincident, Audiokinesis, Merlin and Devore will provide the
full musical experience (or darned close to it) without much sacrifice, if any.

Tvad, I thought speaker/tube compatibility was all about the impedance curve, and that low efficiency speakers, with benign impedance curves, simply required more power.
Phaelon (Threads | Answers)

That's true.

The OP's speakers were measured 85db by Stereophile (manufacturer's spec is 87db). As has been mentioned earlier, this would require 200-300 wpc.

Since the OP's price range is $3000, I think most tube amps are eliminated from his wish list, since there are few tube amps that put out 200-300wpc, let alone in his price range.

Atma-Sphere MA-2 fit the bill, but they cost $32,500.

the sub is not very "tight" as I prefer, that
may be definition.
I don't understand everything I know...
Keslerd (Threads)

Tight bass with a subwoofer is often very dependent on placement of the sub.

Research a placement guide. ACI has excellent information on their website, as
I'm certain does Velodyne.

Experiment with proper placement, including facing the driver toward the
listening position and facing sideways into the room, and crossover point, and
I'll bet you discover a position where the bass tightens and integrates
significantly.

03-28-09: Kijanki
Tvad - I found bass to be directional in spite of claims tha it is not and some LP recording that were mono below 150 Hz.

I think this statement is contradictory. Mono below 150Hz indicates non-directional bass.

Also - don't you feel that speakers like Revel Saloon designed to go very low are better choice than smaller speakers + sub.
Kijanki (Threads | Answers)

Yes, but that's not helpful to the OP, who has indicated his intention to keep his bookshelf speakers.

Most of us start where Keslerd is presently, i.e. not wanting to spend $500/6 ft of wire.

I know I did.

It's a journey unique to each individual. Price barriers break down in due time when the benefits begin to be heard.