How low do they go?
Of the 13 here with a figure quoted, most are rated between 44Hz and 110Hz, with a median of 70Hz. 0 of them are quoted at 40Hz or below, which is roughly where a soundtrack's low effects and the bottom of a bass guitar live. Makers measure this differently, so use the figure to rank models rather than as a promise.
What do they cost?
Most sit between $600 and $4,500, with a median of $1,200 and a full range of $279 to $6,000. Prices are for a pair unless the listing says otherwise. These are the current asking prices we hold, not sale prices, and they move - check the retailer before deciding.
What amplifier do they need?
Sensitivity here is mostly 87.0dB to 93.0dB, median 88.0dB. 7 of the 13 that state a nominal impedance are 4 ohms. Every 3dB of sensitivity is worth as much as doubling the amplifier's power, so a sensitive speaker needs far less amplifier than an insensitive one of the same size. Read the minimum impedance as well: a nominal 8 ohm speaker that dips to 3 ohms is the harder load.
How big are they?
Most are 297mm to 866mm tall, median 437mm, and weigh 1.6kg to 9.0kg, median 6.8kg. Every listing gives height, width and depth in both inches and millimetres, so measure the space before you order rather than after.
How close to the wall can they go?
Flat against it, which is what they are designed for - the maker has already allowed for the bass reinforcement the wall gives. That is exactly why a normal bookshelf speaker sounds thick when it is pushed against a wall and one of these does not.