How low do they go?
Of the 350 here with a figure quoted, most are rated between 38Hz and 65Hz, with a median of 50Hz. 62 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 $279 and $6,499, with a median of $1,000 and a full range of $99 to $22,000. 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 85.0dB to 90.0dB, median 87.0dB. 173 of the 351 that state a nominal impedance are 8 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.
Can they be bi-wired or bi-amped?
114 of the 266 with the connection recorded have two sets of binding posts, so those can be bi-wired or bi-amped. It is worth knowing before you buy cable, but it is a long way down the list of things that change the sound - position and room treatment come first.
How big are they?
Most are 260mm to 482mm tall, median 345mm, and weigh 4.0kg to 16.0kg, median 7.5kg. Every listing gives height, width and depth in both inches and millimetres, so measure the space before you order rather than after.
Do they need stands?
Almost always, yes. A bookshelf speaker is designed with the tweeter at seated ear height and with air around the cabinet. Pushed into a shelf or a cupboard it gains a thick, boomy bass and loses the imaging that made it worth buying. Budget for stands, or for a shelf you can place it on rather than in.